From: Davidlohr Bueso <dave@stgolabs.net>
To: colyli@suse.de, kent.overstreet@gmail.com
Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org,
dave@stgolabs.net, Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH] bcache: optimize barrier usage for Rmw atomic bitops
Date: Wed, 29 Jan 2020 10:08:02 -0800 [thread overview]
Message-ID: <20200129180802.24626-1-dave@stgolabs.net> (raw)
We can avoid the unnecessary barrier on non LL/SC architectures,
such as x86. Instead, use the smp_mb__after_atomic().
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
drivers/md/bcache/writeback.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 4a40f9eadeaf..284ff10f480f 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -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,
--
2.16.4
next reply other threads:[~2020-01-29 18:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 18:08 Davidlohr Bueso [this message]
2020-03-20 15:24 ` Coly Li
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