Messages in this thread Patch in this message | | | Date | Wed, 22 Apr 2020 21:20:48 -0000 | From | "tip-bot2 for Giovanni Gherdovich" <> | Subject | [tip: sched/urgent] x86, sched: Account for CPUs with less than 4 cores in freq. invariance |
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The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 23ccee22e834eca236b9a20989caf6905bd6954a Gitweb: https://git.kernel.org/tip/23ccee22e834eca236b9a20989caf6905bd6954a Author: Giovanni Gherdovich <ggherdovich@suse.cz> AuthorDate: Thu, 16 Apr 2020 07:47:43 +02:00 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Wed, 22 Apr 2020 23:10:13 +02:00
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 --- 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 3a318ec..5d346b7 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; }
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