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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>
54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef ARCH_X86_CPU_H
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#define ARCH_X86_CPU_H
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/* attempt to consolidate cpu attributes */
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struct cpu_dev {
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const char *c_vendor;
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/* some have two possibilities for cpuid string */
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const char *c_ident[2];
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void (*c_early_init)(struct cpuinfo_x86 *);
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void (*c_bsp_init)(struct cpuinfo_x86 *);
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void (*c_init)(struct cpuinfo_x86 *);
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void (*c_identify)(struct cpuinfo_x86 *);
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void (*c_detect_tlb)(struct cpuinfo_x86 *);
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void (*c_bsp_resume)(struct cpuinfo_x86 *);
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int c_x86_vendor;
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#ifdef CONFIG_X86_32
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/* Optional vendor specific routine to obtain the cache size. */
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unsigned int (*legacy_cache_size)(struct cpuinfo_x86 *,
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unsigned int);
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/* Family/stepping-based lookup table for model names. */
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struct legacy_cpu_model_info {
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int family;
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const char *model_names[16];
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} legacy_models[5];
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#endif
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};
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struct _tlb_table {
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unsigned char descriptor;
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char tlb_type;
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unsigned int entries;
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/* unsigned int ways; */
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char info[128];
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};
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#define cpu_dev_register(cpu_devX) \
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static const struct cpu_dev *const __cpu_dev_##cpu_devX __used \
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__attribute__((__section__(".x86_cpu_dev.init"))) = \
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&cpu_devX;
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extern const struct cpu_dev *const __x86_cpu_dev_start[],
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*const __x86_cpu_dev_end[];
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extern void get_cpu_cap(struct cpuinfo_x86 *c);
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extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
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unsigned int aperfmperf_get_khz(int cpu);
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#endif /* ARCH_X86_CPU_H */
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