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x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0

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Be defensive against the case where the processor reports a base_freq
larger than turbo_freq (the ratio would be zero).

Fixes: 1567c3e346 ("x86, sched: Add support for frequency invariance")
Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20200531182453.15254-4-ggherdovich@suse.cz
This commit is contained in:
Giovanni Gherdovich 2020-05-31 20:24:53 +02:00 committed by Peter Zijlstra
parent 51beea8862
commit f4291df103
1 changed files with 9 additions and 2 deletions
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11
arch/x86/kernel/smpboot.c
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@ -1977,6 +1977,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
static bool intel_set_max_freq_ratio(void)
{
u64 base_freq, turbo_freq;
u64 turbo_ratio;
if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
goto out;
@ -2010,9 +2011,15 @@ static bool intel_set_max_freq_ratio(void)
return false;
}
arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE,
base_freq);
turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);
if (!turbo_ratio) {
pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");
return false;
}
arch_turbo_freq_ratio = turbo_ratio;
arch_set_max_freq_ratio(turbo_disabled());
return true;
}