diff options
| author | Giovanni Gherdovich <ggherdovich@suse.cz> | 2020-04-16 07:47:43 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-04-22 23:10:13 +0200 |
| commit | 23ccee22e834eca236b9a20989caf6905bd6954a (patch) | |
| tree | eef4b477b47cbcf926942e4eb7cf74799177edea /arch | |
| parent | 9a6c2c3c7a73ce315c57c1b002caad6fcc858d0f (diff) | |
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')
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 11 |
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; } |