mm/vmstat: use this_cpu_try_cmpxchg in mod_{zone,node}_state

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Use this_cpu_try_cmpxchg instead of this_cpu_cmpxchg (*ptr, old, new) ==
old in mod_zone_state and mod_node_state.  x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg (and
related move instruction in front of cmpxchg).

Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg
fails.  There is no need to re-read the value in the loop.

No functional change intended.

Link: https://lkml.kernel.org/r/20230904150917.8318-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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This commit is contained in:

Uros Bizjak 2023-09-04 17:08:49 +02:00 • committed by Andrew Morton

parent 91e79d22be

commit 77cd814835

1 changed files with 10 additions and 8 deletions

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mm/vmstat.c

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