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sched/core: Fix arch_scale_freq_tick() on tickless systems

Phil Auld requested to merge prauld/centos-stream-9:bz1996625 into main

Bugzilla: https://bugzilla.redhat.com/1996625

commit 7fb3ff22ad8772bbf0e3ce1ef3eb7b09f431807f
Author: Yair Podemsky ypodemsk@redhat.com
Date: Wed Nov 30 14:51:21 2022 +0200

sched/core: Fix arch_scale_freq_tick() on tickless systems  

In order for the scheduler to be frequency invariant we measure the  
ratio between the maximum CPU frequency and the actual CPU frequency.  

During long tickless periods of time the calculations that keep track  
of that might overflow, in the function scale_freq_tick():  

  if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))  
          goto error;  

eventually forcing the kernel to disable the feature for all CPUs,  
and show the warning message:  

   "Scheduler frequency invariance went wobbly, disabling!".  

Let's avoid that by limiting the frequency invariant calculations  
to CPUs with regular tick.  

Fixes: e2b0d619b400 ("x86, sched: check for counters overflow in frequency invariant accounting")  
Suggested-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>  
Signed-off-by: Yair Podemsky <ypodemsk@redhat.com>  
Signed-off-by: Ingo Molnar <mingo@kernel.org>  
Reviewed-by: Valentin Schneider <vschneid@redhat.com>  
Acked-by: Giovanni Gherdovich <ggherdovich@suse.cz>  
Link: https://lore.kernel.org/r/20221130125121.34407-1-ypodemsk@redhat.com

Signed-off-by: Phil Auld pauld@redhat.com

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