Commit b004aa86 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Jens Axboe
Browse files

bcache: optimize barrier usage for Rmw atomic bitops 



We can avoid the unnecessary barrier on non LL/SC architectures,
such as x86. Instead, use the smp_mb__after_atomic().

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarColy Li <colyli@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9876e386

drivers/md/bcache/writeback.c

+3 −3
Original line number Diff line number Diff line
@@ -183,7 +183,7 @@ static void update_writeback_rate(struct work_struct *work) 
	 */

	set_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);

	/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */

	smp_mb();

	smp_mb__after_atomic();



	/*

	 * CACHE_SET_IO_DISABLE might be set via sysfs interface,
@@ -193,7 +193,7 @@ static void update_writeback_rate(struct work_struct *work) 
	    test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {

		clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);

		/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */

		smp_mb();

		smp_mb__after_atomic();

		return;

	}
@@ -229,7 +229,7 @@ static void update_writeback_rate(struct work_struct *work) 
	 */

	clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);

	/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */

	smp_mb();

	smp_mb__after_atomic();

}



static unsigned int writeback_delay(struct cached_dev *dc,

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