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x86, sched: Add support for frequency invariance on ATOM_GOLDMONT*

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The scheduler needs the ratio freq_curr/freq_max for frequency-invariant
accounting. On GOLDMONT (aka Apollo Lake), GOLDMONT_D (aka Denverton) and
GOLDMONT_PLUS CPUs (aka Gemini Lake) set freq_max to the highest frequency
reported by the CPU.

The encoding of turbo ratios for GOLDMONT* is identical to the one for
SKYLAKE_X, but we treat the Atom case apart because we want to set freq_max to
a higher value, thus the ratio freq_curr/freq_max to be lower, leading to more
conservative frequency selections (favoring power efficiency).

Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20200122151617.531-5-ggherdovich@suse.cz
This commit is contained in:
Giovanni Gherdovich 2020-01-22 16:16:15 +01:00 committed by Ingo Molnar
parent 8bea0dfb4a
commit eacf0474ae
1 changed files with 8 additions and 4 deletions
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12
arch/x86/kernel/smpboot.c
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@ -1795,6 +1795,10 @@ void native_play_dead(void)
* which would ignore the entire turbo range (a conspicuous part, making
* freq_curr/freq_max always maxed out).
*
* An exception to the heuristic above is the Atom uarch, where we choose the
* highest turbo level for freq_max since Atom's are generally oriented towards
* power efficiency.
*
* Setting freq_max to anything less than the 1C turbo ratio makes the ratio
* freq_curr / freq_max to eventually grow >1, in which case we clip it to 1.
*/
@ -1937,18 +1941,18 @@ static bool intel_set_max_freq_ratio(void)
/*
* TODO: add support for:
*
* - Atom Goldmont
* - Atom Silvermont
*/
u64 base_freq = 1, turbo_freq = 1;
if (x86_match_cpu(has_glm_turbo_ratio_limits))
return false;
if (turbo_disabled())
goto out;
if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
goto out;
if (knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
goto out;