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linux/arch/powerpc/kernel/time.c

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/*
* Common time routines among all ppc machines.
*
* Written by Cort Dougan (cort@cs.nmt.edu) to merge
* Paul Mackerras' version and mine for PReP and Pmac.
* MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
* Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
*
* First round of bugfixes by Gabriel Paubert (paubert@iram.es)
* to make clock more stable (2.4.0-test5). The only thing
* that this code assumes is that the timebases have been synchronized
* by firmware on SMP and are never stopped (never do sleep
* on SMP then, nap and doze are OK).
*
* Speeded up do_gettimeofday by getting rid of references to
* xtime (which required locks for consistency). (mikejc@us.ibm.com)
*
* TODO (not necessarily in this file):
* - improve precision and reproducibility of timebase frequency
* measurement at boot time. (for iSeries, we calibrate the timebase
* against the Titan chip's clock.)
* - for astronomical applications: add a new function to get
* non ambiguous timestamps even around leap seconds. This needs
* a new timestamp format and a good name.
*
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/kernel_stat.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/cpu.h>
#include <linux/security.h>
#include <linux/percpu.h>
#include <linux/rtc.h>
#include <linux/jiffies.h>
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
#include <linux/posix-timers.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/nvram.h>
#include <asm/cache.h>
#include <asm/machdep.h>
#include <asm/uaccess.h>
#include <asm/time.h>
#include <asm/prom.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/smp.h>
#include <asm/vdso_datapage.h>
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#endif
#ifdef CONFIG_PPC_ISERIES
#include <asm/iseries/it_lp_queue.h>
#include <asm/iseries/hv_call_xm.h>
#endif
#include <asm/smp.h>
/* keep track of when we need to update the rtc */
time_t last_rtc_update;
extern int piranha_simulator;
#ifdef CONFIG_PPC_ISERIES
unsigned long iSeries_recal_titan = 0;
unsigned long iSeries_recal_tb = 0;
static unsigned long first_settimeofday = 1;
#endif
/* The decrementer counts down by 128 every 128ns on a 601. */
#define DECREMENTER_COUNT_601 (1000000000 / HZ)
#define XSEC_PER_SEC (1024*1024)
#ifdef CONFIG_PPC64
#define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
#else
/* compute ((xsec << 12) * max) >> 32 */
#define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
#endif
unsigned long tb_ticks_per_jiffy;
unsigned long tb_ticks_per_usec = 100; /* sane default */
EXPORT_SYMBOL(tb_ticks_per_usec);
unsigned long tb_ticks_per_sec;
EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
u64 tb_to_xs;
unsigned tb_to_us;
#define TICKLEN_SCALE (SHIFT_SCALE - 10)
u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
u64 ticklen_to_xs; /* 0.64 fraction */
/* If last_tick_len corresponds to about 1/HZ seconds, then
last_tick_len << TICKLEN_SHIFT will be about 2^63. */
#define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL_GPL(rtc_lock);
u64 tb_to_ns_scale;
unsigned tb_to_ns_shift;
struct gettimeofday_struct do_gtod;
extern unsigned long wall_jiffies;
extern struct timezone sys_tz;
static long timezone_offset;
unsigned long ppc_proc_freq;
unsigned long ppc_tb_freq;
u64 tb_last_jiffy __cacheline_aligned_in_smp;
unsigned long tb_last_stamp;
/*
* Note that on ppc32 this only stores the bottom 32 bits of
* the timebase value, but that's enough to tell when a jiffy
* has passed.
*/
DEFINE_PER_CPU(unsigned long, last_jiffy);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
/*
* Factors for converting from cputime_t (timebase ticks) to
* jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
* These are all stored as 0.64 fixed-point binary fractions.
*/
u64 __cputime_jiffies_factor;
EXPORT_SYMBOL(__cputime_jiffies_factor);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
u64 __cputime_msec_factor;
EXPORT_SYMBOL(__cputime_msec_factor);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
u64 __cputime_sec_factor;
EXPORT_SYMBOL(__cputime_sec_factor);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
u64 __cputime_clockt_factor;
EXPORT_SYMBOL(__cputime_clockt_factor);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
static void calc_cputime_factors(void)
{
struct div_result res;
div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
__cputime_jiffies_factor = res.result_low;
div128_by_32(1000, 0, tb_ticks_per_sec, &res);
__cputime_msec_factor = res.result_low;
div128_by_32(1, 0, tb_ticks_per_sec, &res);
__cputime_sec_factor = res.result_low;
div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
__cputime_clockt_factor = res.result_low;
}
/*
* Read the PURR on systems that have it, otherwise the timebase.
*/
static u64 read_purr(void)
{
if (cpu_has_feature(CPU_FTR_PURR))
return mfspr(SPRN_PURR);
return mftb();
}
/*
* Account time for a transition between system, hard irq
* or soft irq state.
*/
void account_system_vtime(struct task_struct *tsk)
{
u64 now, delta;
unsigned long flags;
local_irq_save(flags);
now = read_purr();
delta = now - get_paca()->startpurr;
get_paca()->startpurr = now;
if (!in_interrupt()) {
delta += get_paca()->system_time;
get_paca()->system_time = 0;
}
account_system_time(tsk, 0, delta);
local_irq_restore(flags);
}
/*
* Transfer the user and system times accumulated in the paca
* by the exception entry and exit code to the generic process
* user and system time records.
* Must be called with interrupts disabled.
*/
void account_process_vtime(struct task_struct *tsk)
{
cputime_t utime;
utime = get_paca()->user_time;
get_paca()->user_time = 0;
account_user_time(tsk, utime);
}
static void account_process_time(struct pt_regs *regs)
{
int cpu = smp_processor_id();
account_process_vtime(current);
run_local_timers();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, user_mode(regs));
scheduler_tick();
run_posix_cpu_timers(current);
}
#ifdef CONFIG_PPC_SPLPAR
/*
* Stuff for accounting stolen time.
*/
struct cpu_purr_data {
int initialized; /* thread is running */
u64 tb0; /* timebase at origin time */
u64 purr0; /* PURR at origin time */
u64 tb; /* last TB value read */
u64 purr; /* last PURR value read */
u64 stolen; /* stolen time so far */
spinlock_t lock;
};
static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
static void snapshot_tb_and_purr(void *data)
{
struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
p->tb0 = mftb();
p->purr0 = mfspr(SPRN_PURR);
p->tb = p->tb0;
p->purr = 0;
wmb();
p->initialized = 1;
}
/*
* Called during boot when all cpus have come up.
*/
void snapshot_timebases(void)
{
int cpu;
if (!cpu_has_feature(CPU_FTR_PURR))
return;
for_each_cpu(cpu)
spin_lock_init(&per_cpu(cpu_purr_data, cpu).lock);
on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1);
}
void calculate_steal_time(void)
{
u64 tb, purr, t0;
s64 stolen;
struct cpu_purr_data *p0, *pme, *phim;
int cpu;
if (!cpu_has_feature(CPU_FTR_PURR))
return;
cpu = smp_processor_id();
pme = &per_cpu(cpu_purr_data, cpu);
if (!pme->initialized)
return; /* this can happen in early boot */
p0 = &per_cpu(cpu_purr_data, cpu & ~1);
phim = &per_cpu(cpu_purr_data, cpu ^ 1);
spin_lock(&p0->lock);
tb = mftb();
purr = mfspr(SPRN_PURR) - pme->purr0;
if (!phim->initialized || !cpu_online(cpu ^ 1)) {
stolen = (tb - pme->tb) - (purr - pme->purr);
} else {
t0 = pme->tb0;
if (phim->tb0 < t0)
t0 = phim->tb0;
stolen = phim->tb - t0 - phim->purr - purr - p0->stolen;
}
if (stolen > 0) {
account_steal_time(current, stolen);
p0->stolen += stolen;
}
pme->tb = tb;
pme->purr = purr;
spin_unlock(&p0->lock);
}
/*
* Must be called before the cpu is added to the online map when
* a cpu is being brought up at runtime.
*/
static void snapshot_purr(void)
{
int cpu;
u64 purr;
struct cpu_purr_data *p0, *pme, *phim;
unsigned long flags;
if (!cpu_has_feature(CPU_FTR_PURR))
return;
cpu = smp_processor_id();
pme = &per_cpu(cpu_purr_data, cpu);
p0 = &per_cpu(cpu_purr_data, cpu & ~1);
phim = &per_cpu(cpu_purr_data, cpu ^ 1);
spin_lock_irqsave(&p0->lock, flags);
pme->tb = pme->tb0 = mftb();
purr = mfspr(SPRN_PURR);
if (!phim->initialized) {
pme->purr = 0;
pme->purr0 = purr;
} else {
/* set p->purr and p->purr0 for no change in p0->stolen */
pme->purr = phim->tb - phim->tb0 - phim->purr - p0->stolen;
pme->purr0 = purr - pme->purr;
}
pme->initialized = 1;
spin_unlock_irqrestore(&p0->lock, flags);
}
#endif /* CONFIG_PPC_SPLPAR */
#else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
#define calc_cputime_factors()
#define account_process_time(regs) update_process_times(user_mode(regs))
#define calculate_steal_time() do { } while (0)
#endif
#if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
#define snapshot_purr() do { } while (0)
#endif
/*
* Called when a cpu comes up after the system has finished booting,
* i.e. as a result of a hotplug cpu action.
*/
void snapshot_timebase(void)
{
__get_cpu_var(last_jiffy) = get_tb();
snapshot_purr();
}
void __delay(unsigned long loops)
{
unsigned long start;
int diff;
if (__USE_RTC()) {
start = get_rtcl();
do {
/* the RTCL register wraps at 1000000000 */
diff = get_rtcl() - start;
if (diff < 0)
diff += 1000000000;
} while (diff < loops);
} else {
start = get_tbl();
while (get_tbl() - start < loops)
HMT_low();
HMT_medium();
}
}
EXPORT_SYMBOL(__delay);
void udelay(unsigned long usecs)
{
__delay(tb_ticks_per_usec * usecs);
}
EXPORT_SYMBOL(udelay);
static __inline__ void timer_check_rtc(void)
{
/*
* update the rtc when needed, this should be performed on the
* right fraction of a second. Half or full second ?
* Full second works on mk48t59 clocks, others need testing.
* Note that this update is basically only used through
* the adjtimex system calls. Setting the HW clock in
* any other way is a /dev/rtc and userland business.
* This is still wrong by -0.5/+1.5 jiffies because of the
* timer interrupt resolution and possible delay, but here we
* hit a quantization limit which can only be solved by higher
* resolution timers and decoupling time management from timer
* interrupts. This is also wrong on the clocks
* which require being written at the half second boundary.
* We should have an rtc call that only sets the minutes and
* seconds like on Intel to avoid problems with non UTC clocks.
*/
if (ppc_md.set_rtc_time && ntp_synced() &&
xtime.tv_sec - last_rtc_update >= 659 &&
abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ) {
struct rtc_time tm;
to_tm(xtime.tv_sec + 1 + timezone_offset, &tm);
tm.tm_year -= 1900;
tm.tm_mon -= 1;
if (ppc_md.set_rtc_time(&tm) == 0)
last_rtc_update = xtime.tv_sec + 1;
else
/* Try again one minute later */
last_rtc_update += 60;
}
}
/*
* This version of gettimeofday has microsecond resolution.
*/
static inline void __do_gettimeofday(struct timeval *tv, u64 tb_val)
{
unsigned long sec, usec;
u64 tb_ticks, xsec;
struct gettimeofday_vars *temp_varp;
u64 temp_tb_to_xs, temp_stamp_xsec;
/*
* These calculations are faster (gets rid of divides)
* if done in units of 1/2^20 rather than microseconds.
* The conversion to microseconds at the end is done
* without a divide (and in fact, without a multiply)
*/
temp_varp = do_gtod.varp;
tb_ticks = tb_val - temp_varp->tb_orig_stamp;
temp_tb_to_xs = temp_varp->tb_to_xs;
temp_stamp_xsec = temp_varp->stamp_xsec;
xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
sec = xsec / XSEC_PER_SEC;
usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
usec = SCALE_XSEC(usec, 1000000);
tv->tv_sec = sec;
tv->tv_usec = usec;
}
void do_gettimeofday(struct timeval *tv)
{
if (__USE_RTC()) {
/* do this the old way */
unsigned long flags, seq;
unsigned int sec, nsec, usec;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
sec = xtime.tv_sec;
nsec = xtime.tv_nsec + tb_ticks_since(tb_last_stamp);
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
usec = nsec / 1000;
while (usec >= 1000000) {
usec -= 1000000;
++sec;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
return;
}
__do_gettimeofday(tv, get_tb());
}
EXPORT_SYMBOL(do_gettimeofday);
/*
* There are two copies of tb_to_xs and stamp_xsec so that no
* lock is needed to access and use these values in
* do_gettimeofday. We alternate the copies and as long as a
* reasonable time elapses between changes, there will never
* be inconsistent values. ntpd has a minimum of one minute
* between updates.
*/
static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
u64 new_tb_to_xs)
{
unsigned temp_idx;
struct gettimeofday_vars *temp_varp;
temp_idx = (do_gtod.var_idx == 0);
temp_varp = &do_gtod.vars[temp_idx];
temp_varp->tb_to_xs = new_tb_to_xs;
temp_varp->tb_orig_stamp = new_tb_stamp;
temp_varp->stamp_xsec = new_stamp_xsec;
smp_mb();
do_gtod.varp = temp_varp;
do_gtod.var_idx = temp_idx;
/*
* tb_update_count is used to allow the userspace gettimeofday code
* to assure itself that it sees a consistent view of the tb_to_xs and
* stamp_xsec variables. It reads the tb_update_count, then reads
* tb_to_xs and stamp_xsec and then reads tb_update_count again. If
* the two values of tb_update_count match and are even then the
* tb_to_xs and stamp_xsec values are consistent. If not, then it
* loops back and reads them again until this criteria is met.
* We expect the caller to have done the first increment of
* vdso_data->tb_update_count already.
*/
vdso_data->tb_orig_stamp = new_tb_stamp;
vdso_data->stamp_xsec = new_stamp_xsec;
vdso_data->tb_to_xs = new_tb_to_xs;
vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
smp_wmb();
++(vdso_data->tb_update_count);
}
/*
* When the timebase - tb_orig_stamp gets too big, we do a manipulation
* between tb_orig_stamp and stamp_xsec. The goal here is to keep the
* difference tb - tb_orig_stamp small enough to always fit inside a
* 32 bits number. This is a requirement of our fast 32 bits userland
* implementation in the vdso. If we "miss" a call to this function
* (interrupt latency, CPU locked in a spinlock, ...) and we end up
* with a too big difference, then the vdso will fallback to calling
* the syscall
*/
static __inline__ void timer_recalc_offset(u64 cur_tb)
{
unsigned long offset;
u64 new_stamp_xsec;
u64 tlen, t2x;
u64 tb, xsec_old, xsec_new;
struct gettimeofday_vars *varp;
if (__USE_RTC())
return;
tlen = current_tick_length();
offset = cur_tb - do_gtod.varp->tb_orig_stamp;
if (tlen == last_tick_len && offset < 0x80000000u)
return;
if (tlen != last_tick_len) {
t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs);
last_tick_len = tlen;
} else
t2x = do_gtod.varp->tb_to_xs;
new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
do_div(new_stamp_xsec, 1000000000);
new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
++vdso_data->tb_update_count;
smp_mb();
/*
* Make sure time doesn't go backwards for userspace gettimeofday.
*/
tb = get_tb();
varp = do_gtod.varp;
xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs)
+ varp->stamp_xsec;
xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec;
if (xsec_new < xsec_old)
new_stamp_xsec += xsec_old - xsec_new;
update_gtod(cur_tb, new_stamp_xsec, t2x);
}
#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
unsigned long pc = instruction_pointer(regs);
if (in_lock_functions(pc))
return regs->link;
return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif
#ifdef CONFIG_PPC_ISERIES
/*
* This function recalibrates the timebase based on the 49-bit time-of-day
* value in the Titan chip. The Titan is much more accurate than the value
* returned by the service processor for the timebase frequency.
*/
static void iSeries_tb_recal(void)
{
struct div_result divres;
unsigned long titan, tb;
tb = get_tb();
titan = HvCallXm_loadTod();
if ( iSeries_recal_titan ) {
unsigned long tb_ticks = tb - iSeries_recal_tb;
unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
char sign = '+';
/* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
if ( tick_diff < 0 ) {
tick_diff = -tick_diff;
sign = '-';
}
if ( tick_diff ) {
if ( tick_diff < tb_ticks_per_jiffy/25 ) {
printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
new_tb_ticks_per_jiffy, sign, tick_diff );
tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
tb_ticks_per_sec = new_tb_ticks_per_sec;
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
calc_cputime_factors();
div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
tb_to_xs = divres.result_low;
do_gtod.varp->tb_to_xs = tb_to_xs;
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
vdso_data->tb_to_xs = tb_to_xs;
}
else {
printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
" new tb_ticks_per_jiffy = %lu\n"
" old tb_ticks_per_jiffy = %lu\n",
new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
}
}
}
iSeries_recal_titan = titan;
iSeries_recal_tb = tb;
}
#endif
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
* in the lppaca and call the hypervisor if the virtual
* decrementer is less than the current value in the hardware
* decrementer. (almost always the new decrementer value will
* be greater than the current hardware decementer so the hypervisor
* call will not be needed)
*/
/*
* timer_interrupt - gets called when the decrementer overflows,
* with interrupts disabled.
*/
void timer_interrupt(struct pt_regs * regs)
{
int next_dec;
int cpu = smp_processor_id();
unsigned long ticks;
#ifdef CONFIG_PPC32
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);
#endif
irq_enter();
profile_tick(CPU_PROFILING, regs);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
calculate_steal_time();
#ifdef CONFIG_PPC_ISERIES
get_lppaca()->int_dword.fields.decr_int = 0;
#endif
while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu)))
>= tb_ticks_per_jiffy) {
/* Update last_jiffy */
per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy;
/* Handle RTCL overflow on 601 */
if (__USE_RTC() && per_cpu(last_jiffy, cpu) >= 1000000000)
per_cpu(last_jiffy, cpu) -= 1000000000;
/*
* We cannot disable the decrementer, so in the period
* between this cpu's being marked offline in cpu_online_map
* and calling stop-self, it is taking timer interrupts.
* Avoid calling into the scheduler rebalancing code if this
* is the case.
*/
if (!cpu_is_offline(cpu))
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
account_process_time(regs);
/*
* No need to check whether cpu is offline here; boot_cpuid
* should have been fixed up by now.
*/
if (cpu != boot_cpuid)
continue;
write_seqlock(&xtime_lock);
tb_last_jiffy += tb_ticks_per_jiffy;
tb_last_stamp = per_cpu(last_jiffy, cpu);
do_timer(regs);
timer_recalc_offset(tb_last_jiffy);
timer_check_rtc();
write_sequnlock(&xtime_lock);
}
next_dec = tb_ticks_per_jiffy - ticks;
set_dec(next_dec);
#ifdef CONFIG_PPC_ISERIES
if (hvlpevent_is_pending())
process_hvlpevents(regs);
#endif
#ifdef CONFIG_PPC64
/* collect purr register values often, for accurate calculations */
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
cu->current_tb = mfspr(SPRN_PURR);
}
#endif
irq_exit();
}
void wakeup_decrementer(void)
{
unsigned long ticks;
/*
* The timebase gets saved on sleep and restored on wakeup,
* so all we need to do is to reset the decrementer.
*/
ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
if (ticks < tb_ticks_per_jiffy)
ticks = tb_ticks_per_jiffy - ticks;
else
ticks = 1;
set_dec(ticks);
}
#ifdef CONFIG_SMP
void __init smp_space_timers(unsigned int max_cpus)
{
int i;
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
unsigned long half = tb_ticks_per_jiffy / 2;
unsigned long offset = tb_ticks_per_jiffy / max_cpus;
unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid);
/* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
previous_tb -= tb_ticks_per_jiffy;
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
/*
* The stolen time calculation for POWER5 shared-processor LPAR
* systems works better if the two threads' timebase interrupts
* are staggered by half a jiffy with respect to each other.
*/
for_each_cpu(i) {
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
if (i == boot_cpuid)
continue;
if (i == (boot_cpuid ^ 1))
per_cpu(last_jiffy, i) =
per_cpu(last_jiffy, boot_cpuid) - half;
else if (i & 1)
per_cpu(last_jiffy, i) =
per_cpu(last_jiffy, i ^ 1) + half;
else {
previous_tb += offset;
per_cpu(last_jiffy, i) = previous_tb;
}
}
}
#endif
/*
* Scheduler clock - returns current time in nanosec units.
*
* Note: mulhdu(a, b) (multiply high double unsigned) returns
* the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
* are 64-bit unsigned numbers.
*/
unsigned long long sched_clock(void)
{
if (__USE_RTC())
return get_rtc();
return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
}
int do_settimeofday(struct timespec *tv)
{
time_t wtm_sec, new_sec = tv->tv_sec;
long wtm_nsec, new_nsec = tv->tv_nsec;
unsigned long flags;
u64 new_xsec;
unsigned long tb_delta;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irqsave(&xtime_lock, flags);
/*
* Updating the RTC is not the job of this code. If the time is
* stepped under NTP, the RTC will be updated after STA_UNSYNC
* is cleared. Tools like clock/hwclock either copy the RTC
* to the system time, in which case there is no point in writing
* to the RTC again, or write to the RTC but then they don't call
* settimeofday to perform this operation.
*/
#ifdef CONFIG_PPC_ISERIES
if (first_settimeofday) {
iSeries_tb_recal();
first_settimeofday = 0;
}
#endif
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_mb();
/*
* Subtract off the number of nanoseconds since the
* beginning of the last tick.
* Note that since we don't increment jiffies_64 anywhere other
* than in do_timer (since we don't have a lost tick problem),
* wall_jiffies will always be the same as jiffies,
* and therefore the (jiffies - wall_jiffies) computation
* has been removed.
*/
tb_delta = tb_ticks_since(tb_last_stamp);
tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
set_normalized_timespec(&xtime, new_sec, new_nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
/* In case of a large backwards jump in time with NTP, we want the
* clock to be updated as soon as the PLL is again in lock.
*/
last_rtc_update = new_sec - 658;
ntp_clear();
new_xsec = xtime.tv_nsec;
if (new_xsec != 0) {
new_xsec *= XSEC_PER_SEC;
do_div(new_xsec, NSEC_PER_SEC);
}
new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC;
update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
write_sequnlock_irqrestore(&xtime_lock, flags);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
void __init generic_calibrate_decr(void)
{
struct device_node *cpu;
unsigned int *fp;
int node_found;
/*
* The cpu node should have a timebase-frequency property
* to tell us the rate at which the decrementer counts.
*/
cpu = of_find_node_by_type(NULL, "cpu");
ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
node_found = 0;
if (cpu) {
fp = (unsigned int *)get_property(cpu, "timebase-frequency",
NULL);
if (fp) {
node_found = 1;
ppc_tb_freq = *fp;
}
}
if (!node_found)
printk(KERN_ERR "WARNING: Estimating decrementer frequency "
"(not found)\n");
ppc_proc_freq = DEFAULT_PROC_FREQ;
node_found = 0;
if (cpu) {
fp = (unsigned int *)get_property(cpu, "clock-frequency",
NULL);
if (fp) {
node_found = 1;
ppc_proc_freq = *fp;
}
}
#ifdef CONFIG_BOOKE
/* Set the time base to zero */
mtspr(SPRN_TBWL, 0);
mtspr(SPRN_TBWU, 0);
/* Clear any pending timer interrupts */
mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
/* Enable decrementer interrupt */
mtspr(SPRN_TCR, TCR_DIE);
#endif
if (!node_found)
printk(KERN_ERR "WARNING: Estimating processor frequency "
"(not found)\n");
of_node_put(cpu);
}
unsigned long get_boot_time(void)
{
struct rtc_time tm;
if (ppc_md.get_boot_time)
return ppc_md.get_boot_time();
if (!ppc_md.get_rtc_time)
return 0;
ppc_md.get_rtc_time(&tm);
return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
/* This function is only called on the boot processor */
void __init time_init(void)
{
unsigned long flags;
unsigned long tm = 0;
struct div_result res;
u64 scale, x;
unsigned shift;
if (ppc_md.time_init != NULL)
timezone_offset = ppc_md.time_init();
if (__USE_RTC()) {
/* 601 processor: dec counts down by 128 every 128ns */
ppc_tb_freq = 1000000000;
tb_last_stamp = get_rtcl();
tb_last_jiffy = tb_last_stamp;
} else {
/* Normal PowerPC with timebase register */
ppc_md.calibrate_decr();
printk(KERN_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
printk(KERN_INFO "time_init: processor frequency = %lu.%.6lu MHz\n",
ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
tb_last_stamp = tb_last_jiffy = get_tb();
}
tb_ticks_per_jiffy = ppc_tb_freq / HZ;
tb_ticks_per_sec = ppc_tb_freq;
tb_ticks_per_usec = ppc_tb_freq / 1000000;
tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
powerpc: Implement accurate task and CPU time accounting This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-23 16:06:59 -07:00
calc_cputime_factors();
/*
* Calculate the length of each tick in ns. It will not be
* exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
* We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
* rounded up.
*/
x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
do_div(x, ppc_tb_freq);
tick_nsec = x;
last_tick_len = x << TICKLEN_SCALE;
/*
* Compute ticklen_to_xs, which is a factor which gets multiplied
* by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
* It is computed as:
* ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
* where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
* which turns out to be N = 51 - SHIFT_HZ.
* This gives the result as a 0.64 fixed-point fraction.
* That value is reduced by an offset amounting to 1 xsec per
* 2^31 timebase ticks to avoid problems with time going backwards
* by 1 xsec when we do timer_recalc_offset due to losing the
* fractional xsec. That offset is equal to ppc_tb_freq/2^51
* since there are 2^20 xsec in a second.
*/
div128_by_32((1ULL << 51) - ppc_tb_freq, 0,
tb_ticks_per_jiffy << SHIFT_HZ, &res);
div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
ticklen_to_xs = res.result_low;
/* Compute tb_to_xs from tick_nsec */
tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
/*
* Compute scale factor for sched_clock.
* The calibrate_decr() function has set tb_ticks_per_sec,
* which is the timebase frequency.
* We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
* the 128-bit result as a 64.64 fixed-point number.
* We then shift that number right until it is less than 1.0,
* giving us the scale factor and shift count to use in
* sched_clock().
*/
div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
scale = res.result_low;
for (shift = 0; res.result_high != 0; ++shift) {
scale = (scale >> 1) | (res.result_high << 63);
res.result_high >>= 1;
}
tb_to_ns_scale = scale;
tb_to_ns_shift = shift;
#ifdef CONFIG_PPC_ISERIES
if (!piranha_simulator)
#endif
tm = get_boot_time();
write_seqlock_irqsave(&xtime_lock, flags);
/* If platform provided a timezone (pmac), we correct the time */
if (timezone_offset) {
sys_tz.tz_minuteswest = -timezone_offset / 60;
sys_tz.tz_dsttime = 0;
tm -= timezone_offset;
}
xtime.tv_sec = tm;
xtime.tv_nsec = 0;
do_gtod.varp = &do_gtod.vars[0];
do_gtod.var_idx = 0;
do_gtod.varp->tb_orig_stamp = tb_last_jiffy;
__get_cpu_var(last_jiffy) = tb_last_stamp;
do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
do_gtod.varp->tb_to_xs = tb_to_xs;
do_gtod.tb_to_us = tb_to_us;
vdso_data->tb_orig_stamp = tb_last_jiffy;
vdso_data->tb_update_count = 0;
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
vdso_data->tb_to_xs = tb_to_xs;
time_freq = 0;
last_rtc_update = xtime.tv_sec;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
write_sequnlock_irqrestore(&xtime_lock, flags);
/* Not exact, but the timer interrupt takes care of this */
set_dec(tb_ticks_per_jiffy);
}
#define FEBRUARY 2
#define STARTOFTIME 1970
#define SECDAY 86400L
#define SECYR (SECDAY * 365)
#define leapyear(year) ((year) % 4 == 0 && \
((year) % 100 != 0 || (year) % 400 == 0))
#define days_in_year(a) (leapyear(a) ? 366 : 365)
#define days_in_month(a) (month_days[(a) - 1])
static int month_days[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
/*
* This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
*/
void GregorianDay(struct rtc_time * tm)
{
int leapsToDate;
int lastYear;
int day;
int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
lastYear = tm->tm_year - 1;
/*
* Number of leap corrections to apply up to end of last year
*/
leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
/*
* This year is a leap year if it is divisible by 4 except when it is
* divisible by 100 unless it is divisible by 400
*
* e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
*/
day = tm->tm_mon > 2 && leapyear(tm->tm_year);
day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
tm->tm_mday;
tm->tm_wday = day % 7;
}
void to_tm(int tim, struct rtc_time * tm)
{
register int i;
register long hms, day;
day = tim / SECDAY;
hms = tim % SECDAY;
/* Hours, minutes, seconds are easy */
tm->tm_hour = hms / 3600;
tm->tm_min = (hms % 3600) / 60;
tm->tm_sec = (hms % 3600) % 60;
/* Number of years in days */
for (i = STARTOFTIME; day >= days_in_year(i); i++)
day -= days_in_year(i);
tm->tm_year = i;
/* Number of months in days left */
if (leapyear(tm->tm_year))
days_in_month(FEBRUARY) = 29;
for (i = 1; day >= days_in_month(i); i++)
day -= days_in_month(i);
days_in_month(FEBRUARY) = 28;
tm->tm_mon = i;
/* Days are what is left over (+1) from all that. */
tm->tm_mday = day + 1;
/*
* Determine the day of week
*/
GregorianDay(tm);
}
/* Auxiliary function to compute scaling factors */
/* Actually the choice of a timebase running at 1/4 the of the bus
* frequency giving resolution of a few tens of nanoseconds is quite nice.
* It makes this computation very precise (27-28 bits typically) which
* is optimistic considering the stability of most processor clock
* oscillators and the precision with which the timebase frequency
* is measured but does not harm.
*/
unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
{
unsigned mlt=0, tmp, err;
/* No concern for performance, it's done once: use a stupid
* but safe and compact method to find the multiplier.
*/
for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
if (mulhwu(inscale, mlt|tmp) < outscale)
mlt |= tmp;
}
/* We might still be off by 1 for the best approximation.
* A side effect of this is that if outscale is too large
* the returned value will be zero.
* Many corner cases have been checked and seem to work,
* some might have been forgotten in the test however.
*/
err = inscale * (mlt+1);
if (err <= inscale/2)
mlt++;
return mlt;
}
/*
* Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
* result.
*/
void div128_by_32(u64 dividend_high, u64 dividend_low,
unsigned divisor, struct div_result *dr)
{
unsigned long a, b, c, d;
unsigned long w, x, y, z;
u64 ra, rb, rc;
a = dividend_high >> 32;
b = dividend_high & 0xffffffff;
c = dividend_low >> 32;
d = dividend_low & 0xffffffff;
w = a / divisor;
ra = ((u64)(a - (w * divisor)) << 32) + b;
rb = ((u64) do_div(ra, divisor) << 32) + c;
x = ra;
rc = ((u64) do_div(rb, divisor) << 32) + d;
y = rb;
do_div(rc, divisor);
z = rc;
dr->result_high = ((u64)w << 32) + x;
dr->result_low = ((u64)y << 32) + z;
}