Revert "x86: CPU: Fix up "cpu MHz" in /proc/cpuinfo"

BugLink: http://bugs.launchpad.net/bugs/1732726
commit ea0ee33988778fb73e4f45e7c73fb735787e2f32 upstream.

This reverts commit 941f5f0f6ef5338814145cf2b813cf1f98873e2f.

Sadly, it turns out that we really can't just do the cross-CPU IPI to
all CPU's to get their proper frequencies, because it's much too
expensive on systems with lots of cores.

So we'll have to revert this for now, and revisit it using a smarter
model (probably doing one system-wide IPI at open time, and doing all
the frequency calculations in parallel).

Reported-by: WANG Chao <chao.wang@ucloud.cn>
Reported-by: Ingo Molnar <mingo@kernel.org>
Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index bffc3a6529162fa4f913f60121fa219f1d0c3770..e17942c131c81e098e8c580624a7c2068cdaec24 100644 (file)
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -21,7 +21,7 @@ obj-y                 += common.o
 obj-y                  += rdrand.o
 obj-y                  += match.o
 obj-y                  += bugs.o
-obj-y                  += aperfmperf.o
+obj-$(CONFIG_CPU_FREQ) += aperfmperf.o
 
 obj-$(CONFIG_PROC_FS)  += proc.o
 obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o

diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
index 957813e0180d278563bf33289c54c7462ca83a8a..0ee83321a3136fcca7a00a3b7e6c375e7a51e13f 100644 (file)
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -42,6 +42,10 @@ static void aperfmperf_snapshot_khz(void *dummy)
        s64 time_delta = ktime_ms_delta(now, s->time);
        unsigned long flags;
 
+       /* Don't bother re-computing within the cache threshold time. */
+       if (time_delta < APERFMPERF_CACHE_THRESHOLD_MS)
+               return;
+
        local_irq_save(flags);
        rdmsrl(MSR_IA32_APERF, aperf);
        rdmsrl(MSR_IA32_MPERF, mperf);
@@ -70,7 +74,6 @@ static void aperfmperf_snapshot_khz(void *dummy)
 
 unsigned int arch_freq_get_on_cpu(int cpu)
 {
-       s64 time_delta;
        unsigned int khz;
 
        if (!cpu_khz)
@@ -79,12 +82,6 @@ unsigned int arch_freq_get_on_cpu(int cpu)
        if (!static_cpu_has(X86_FEATURE_APERFMPERF))
                return 0;
 
-       /* Don't bother re-computing within the cache threshold time. */
-       time_delta = ktime_ms_delta(ktime_get(), per_cpu(samples.time, cpu));
-       khz = per_cpu(samples.khz, cpu);
-       if (khz && time_delta < APERFMPERF_CACHE_THRESHOLD_MS)
-               return khz;
-
        smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1);
        khz = per_cpu(samples.khz, cpu);
        if (khz)

diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 510e695962788770b8dcc3efad52539ff09abdf9..6df621ae62a7c00cb4f95dbf5c41ec83e5397f71 100644 (file)
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -77,10 +77,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
                seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
 
        if (cpu_has(c, X86_FEATURE_TSC)) {
-               unsigned int freq = arch_freq_get_on_cpu(cpu);
+               unsigned int freq = cpufreq_quick_get(cpu);
 
-               if (!freq)
-                       freq = cpufreq_quick_get(cpu);
                if (!freq)
                        freq = cpu_khz;
                seq_printf(m, "cpu MHz\t\t: %u.%03u\n",