sched/core: Use try_cmpxchg in set_nr_{and_not,if}_polling

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Use try_cmpxchg instead of cmpxchg (*ptr, old, new) != old in
set_nr_{and_not,if}_polling. x86 cmpxchg returns success in ZF flag,
so this change saves a compare after cmpxchg.

The definition of cmpxchg based fetch_or was changed in the
same way as atomic_fetch_##op definitions were changed
in e6790e4b5d.

Also declare these two functions as inline to ensure inlining. In the
case of set_nr_and_not_polling, the compiler (gcc) tries to outsmart
itself by constructing the boolean return value with logic operations
on the fetched value, and these extra operations enlarge the function
over the inlining threshold value.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220629151552.6015-1-ubizjak@gmail.com

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Uros Bizjak 2022-06-29 17:15:52 +02:00 • committed by Peter Zijlstra

parent 1fcf54deb7

commit c02d5546ea

1 changed files with 9 additions and 15 deletions

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kernel/sched/core.c

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