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81d68a96a3
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Steven Rostedt 81d68a96a3 ftrace: trace irq disabled critical timings 
This patch adds latency tracing for critical timings
(how long interrupts are disabled for).

 "irqsoff" is added to /debugfs/tracing/available_tracers

Note:
  tracing_max_latency
    also holds the max latency for irqsoff (in usecs).
   (default to large number so one must start latency tracing)

  tracing_thresh
    threshold (in usecs) to always print out if irqs off
    is detected to be longer than stated here.
    If irq_thresh is non-zero, then max_irq_latency
    is ignored.

Here's an example of a trace with ftrace_enabled = 0

=======
preemption latency trace v1.1.5 on 2.6.24-rc7
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
 latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
    -----------------
    | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
    -----------------
 => started at: _spin_lock_irqsave+0x2a/0xb7
 => ended at:   _spin_unlock_irqrestore+0x32/0x5f

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
 swapper-0     1d.s3    0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
 swapper-0     1d.s3  100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
 swapper-0     1d.s3  100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)

vim:ft=help
=======

And this is a trace with ftrace_enabled == 1

=======
preemption latency trace v1.1.5 on 2.6.24-rc7
--------------------------------------------------------------------
 latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
    -----------------
    | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
    -----------------
 => started at: _spin_lock_irqsave+0x2a/0xb7
 => ended at:   _spin_unlock_irqrestore+0x32/0x5f

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
 swapper-0     1dNs3    0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
 swapper-0     1dNs3   46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000])
 swapper-0     1dNs3   46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000])
 swapper-0     1dNs3   46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000])
 swapper-0     1dNs3   47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000])
 swapper-0     1dNs3   47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47)
 swapper-0     1dNs3   97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50)
 swapper-0     1dNs3   98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000])
 swapper-0     1dNs3   99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000])
 swapper-0     1dNs3  101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000])
 swapper-0     1dNs3  102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
 swapper-0     1dNs3  102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)

vim:ft=help
=======

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:32:46 +02:00
..
boot x86: relocs ELF handling - use SELFMAG instead of numeric constant 2008-05-04 20:04:45 +02:00
configs x86: add optimized inlining 2008-04-26 17:44:55 +02:00
crypto [CRYPTO] aes-x86-32: Remove unused return code 2008-04-21 10:19:21 +08:00
ia32 signals: x86 TS_RESTORE_SIGMASK 2008-04-30 08:29:37 -07:00
kernel ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
kvm KVM: LAPIC: ignore pending timers if LVTT is disabled 2008-05-18 14:39:39 +03:00
lguest x86: replace remaining __FUNCTION__ occurances 2008-04-17 17:40:57 +02:00
lib ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
mach-default spelling fixes: arch/i386/ 2007-10-20 01:13:56 +02:00
mach-es7000 i386: es7000 minor cleanups 2007-10-17 20:16:15 +02:00
mach-generic x86: coding style fixes to arch/x86/mach-generic/bigsmp.c 2008-04-17 17:40:48 +02:00
mach-rdc321x x86, rdc321x: remove watchdog file 2008-04-17 17:40:50 +02:00
mach-visws x86: fix compilation error in VisWS 2008-04-24 23:15:44 +02:00
mach-voyager x86, voyager: fix ioremap_nocache() 2008-04-30 23:15:34 +02:00
math-emu x86, fpu: split FPU state from task struct - v5 2008-04-19 19:19:55 +02:00
mm x86: fix crash on cpu hotplug on pat-incapable machines 2008-05-17 22:57:20 +02:00
oprofile x86: oprofile: remove NR_CPUS arrays in arch/x86/oprofile/nmi_int.c 2008-04-19 19:44:58 +02:00
pci PCI: Correct last two HP entries in the bfsort whitelist 2008-05-19 12:21:36 -07:00
power x86: coding style fixes to arch/x86/power/cpu_32.c 2008-04-17 17:40:50 +02:00
vdso x86: add notrace annotations to vsyscall. 2008-05-23 20:31:39 +02:00
video x86: video/fbdev.c: add MODULE_LICENSE 2008-05-04 20:04:46 +02:00
xen pageflags: use proper page flag functions in Xen 2008-04-28 08:58:22 -07:00
Kconfig ftrace: add basic support for gcc profiler instrumentation 2008-05-23 20:31:58 +02:00
Kconfig.cpu x86: CONFIG_X86_ELAN fix 2008-04-30 23:15:35 +02:00
Kconfig.debug x86: Mark OPTIMIZE_INLINING broken 2008-04-30 20:07:22 -07:00
Makefile x86: add subarch support (for headers) to x86_64 2008-04-17 17:41:01 +02:00
Makefile_32.cpu x86: move i386 and x86_64 Makefiles to arch/x86 2007-10-25 22:27:34 +02:00