| Message ID | 20220712152741.7324-1-ubizjak@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] block: Use try_cmpxchg in update_io_ticks | expand |
On Tue, 12 Jul 2022 17:27:41 +0200, Uros Bizjak wrote: > Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in > update_io_ticks. x86 CMPXCHG instruction returns success in ZF flag, > so this change saves a compare after cmpxchg (and related > move instruction in front of cmpxchg). > > No functional change intended. > > [...] Applied, thanks! [1/1] block: Use try_cmpxchg in update_io_ticks commit: 939f9dd040fe1063d884f8f0f89b037093fe2341 Best regards,
diff --git a/block/blk-core.c b/block/blk-core.c index 27fb1357ad4b..628b965356db 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -987,7 +987,7 @@ void update_io_ticks(struct block_device *part, unsigned long now, bool end) again: stamp = READ_ONCE(part->bd_stamp); if (unlikely(time_after(now, stamp))) { - if (likely(cmpxchg(&part->bd_stamp, stamp, now) == stamp)) + if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) __part_stat_add(part, io_ticks, end ? now - stamp : 1); } if (part->bd_partno) {
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in update_io_ticks. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). No functional change intended. Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> --- v2: Split patch from the original big patch --- block/blk-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)