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authorGiovanni Gherdovich <ggherdovich@suse.cz>2020-04-16 08:47:43 +0300
committerPeter Zijlstra <peterz@infradead.org>2020-04-23 00:10:13 +0300
commit23ccee22e834eca236b9a20989caf6905bd6954a (patch)
treeeef4b477b47cbcf926942e4eb7cf74799177edea /arch/x86/kernel/smpboot.c
parent9a6c2c3c7a73ce315c57c1b002caad6fcc858d0f (diff)
downloadlinux-23ccee22e834eca236b9a20989caf6905bd6954a.tar.xz
x86, sched: Account for CPUs with less than 4 cores in freq. invariance
If a CPU has less than 4 physical cores, MSR_TURBO_RATIO_LIMIT will rightfully report that the 4C turbo ratio is zero. In such cases, use the 1C turbo ratio instead for frequency invariance calculations. Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Reported-by: Like Xu <like.xu@linux.intel.com> Reported-by: Neil Rickert <nwr10cst-oslnx@yahoo.com> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com> Link: https://lkml.kernel.org/r/20200416054745.740-3-ggherdovich@suse.cz
Diffstat (limited to 'arch/x86/kernel/smpboot.c')
-rw-r--r--arch/x86/kernel/smpboot.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3a318ec9bc17..5d346b70844b 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1945,18 +1945,23 @@ static bool skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
{
+ u64 msr;
int err;
err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
if (err)
return false;
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, turbo_freq);
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
if (err)
return false;
- *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
- *turbo_freq = (*turbo_freq >> 24) & 0xFF; /* 4C turbo */
+ *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
+ *turbo_freq = (msr >> 24) & 0xFF; /* 4C turbo */
+
+ /* The CPU may have less than 4 cores */
+ if (!*turbo_freq)
+ *turbo_freq = msr & 0xFF; /* 1C turbo */
return true;
}