linux-kernel - [PATCH 01/29] GFS2: Plug on AIL flush

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue,  1 Apr 2014 10:15:13 +0100
From:	Steven Whitehouse <swhiteho@...hat.com>
To:	linux-kernel@...r.kernel.org, cluster-devel@...hat.com
Cc:	Steven Whitehouse <swhiteho@...hat.com>
Subject: [PATCH 01/29] GFS2: Plug on AIL flush

When we do a flush of the AIL list, we are writing out what is
likely to be a lot of small I/Os, which are possibly in an order
which is not ideal performance-wise. Since this is done by calling
filemap_fdatatwrite for each individual inode's address space there
is no overall plugging going on.

In addition to that, we do not always wait for AIL i/o when we flush
it, so that it is possible for things to get left behind on the queue.
By adding explicit plugging here, we reduce the chances of this
being an issues. A quick test using the AIL flush tracepoint shows a
small, but measurable improvement.

Signed-off-by: Steven Whitehouse <swhiteho@...hat.com>

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 9dcb977..1e1bda0 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -18,6 +18,7 @@
 #include <linux/kthread.h>
 #include <linux/freezer.h>
 #include <linux/bio.h>
+#include <linux/blkdev.h>
 #include <linux/writeback.h>
 #include <linux/list_sort.h>

@@ -145,8 +146,10 @@ void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
 {
 	struct list_head *head = &sdp->sd_ail1_list;
 	struct gfs2_trans *tr;
+	struct blk_plug plug;

 	trace_gfs2_ail_flush(sdp, wbc, 1);
+	blk_start_plug(&plug);
 	spin_lock(&sdp->sd_ail_lock);
 restart:
 	list_for_each_entry_reverse(tr, head, tr_list) {
@@ -156,6 +159,7 @@ restart:
 			goto restart;
 	}
 	spin_unlock(&sdp->sd_ail_lock);
+	blk_finish_plug(&plug);
 	trace_gfs2_ail_flush(sdp, wbc, 0);
 }

-- 
1.8.3.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/