Messages in this thread Patch in this message | | | From | Giovanni Gherdovich <> | Subject | [PATCH 2/4] x86, sched: Account for CPUs with less than 4 cores in freq. invariance | Date | Thu, 16 Apr 2020 07:47:43 +0200 |
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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.
Reported-by: Neil Rickert <nwr10cst-oslnx@yahoo.com> Reported-by: Like Xu <like.xu@linux.intel.com> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz> Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") --- arch/x86/kernel/smpboot.c | 11 ++++++++--- 1 file 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; } -- 2.16.4
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