7d5905dc14
After commit890da9cf09(Revert "x86: do not use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz"") the "cpu MHz" number in /proc/cpuinfo on x86 can be either the nominal CPU frequency (which is constant) or the frequency most recently requested by a scaling governor in cpufreq, depending on the cpufreq configuration. That is somewhat inconsistent and is different from what it was before 4.13, so in order to restore the previous behavior, make it report the current CPU frequency like the scaling_cur_freq sysfs file in cpufreq. To that end, modify the /proc/cpuinfo implementation on x86 to use aperfmperf_snapshot_khz() to snapshot the APERF and MPERF feedback registers, if available, and use their values to compute the CPU frequency to be reported as "cpu MHz". However, do that carefully enough to avoid accumulating delays that lead to unacceptable access times for /proc/cpuinfo on systems with many CPUs. Run aperfmperf_snapshot_khz() once on all CPUs asynchronously at the /proc/cpuinfo open time, add a single delay upfront (if necessary) at that point and simply compute the current frequency while running show_cpuinfo() for each individual CPU. Also, to avoid slowing down /proc/cpuinfo accesses too much, reduce the default delay between consecutive APERF and MPERF reads to 10 ms, which should be sufficient to get large enough numbers for the frequency computation in all cases. Fixes:890da9cf09(Revert "x86: do not use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz"") Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org>
59 lines
1.7 KiB
Makefile
59 lines
1.7 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for x86-compatible CPU details, features and quirks
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#
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# Don't trace early stages of a secondary CPU boot
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ifdef CONFIG_FUNCTION_TRACER
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CFLAGS_REMOVE_common.o = -pg
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CFLAGS_REMOVE_perf_event.o = -pg
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endif
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# If these files are instrumented, boot hangs during the first second.
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KCOV_INSTRUMENT_common.o := n
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KCOV_INSTRUMENT_perf_event.o := n
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# Make sure load_percpu_segment has no stackprotector
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nostackp := $(call cc-option, -fno-stack-protector)
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CFLAGS_common.o := $(nostackp)
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obj-y := intel_cacheinfo.o scattered.o topology.o
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obj-y += common.o
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obj-y += rdrand.o
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obj-y += match.o
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obj-y += bugs.o
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obj-y += aperfmperf.o
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obj-y += cpuid-deps.o
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obj-$(CONFIG_PROC_FS) += proc.o
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obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o
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obj-$(CONFIG_CPU_SUP_INTEL) += intel.o
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obj-$(CONFIG_CPU_SUP_AMD) += amd.o
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obj-$(CONFIG_CPU_SUP_CYRIX_32) += cyrix.o
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obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o
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obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o
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obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o
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obj-$(CONFIG_INTEL_RDT) += intel_rdt.o intel_rdt_rdtgroup.o intel_rdt_monitor.o intel_rdt_ctrlmondata.o
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obj-$(CONFIG_X86_MCE) += mcheck/
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obj-$(CONFIG_MTRR) += mtrr/
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obj-$(CONFIG_MICROCODE) += microcode/
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obj-$(CONFIG_X86_LOCAL_APIC) += perfctr-watchdog.o
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obj-$(CONFIG_HYPERVISOR_GUEST) += vmware.o hypervisor.o mshyperv.o
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ifdef CONFIG_X86_FEATURE_NAMES
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quiet_cmd_mkcapflags = MKCAP $@
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cmd_mkcapflags = $(CONFIG_SHELL) $(srctree)/$(src)/mkcapflags.sh $< $@
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cpufeature = $(src)/../../include/asm/cpufeatures.h
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targets += capflags.c
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$(obj)/capflags.c: $(cpufeature) $(src)/mkcapflags.sh FORCE
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$(call if_changed,mkcapflags)
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endif
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clean-files += capflags.c
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