linux-kernel - [PATCH 14/14] skip readahead if the cgroup is congested

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]

Message-Id: <20180703151503.2549-15-josef@toxicpanda.com>
Date:   Tue,  3 Jul 2018 11:15:03 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     axboe@...nel.dk, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, hannes@...xchg.org, tj@...nel.org,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        kernel-team@...com
Cc:     Josef Bacik <jbacik@...com>
Subject: [PATCH 14/14] skip readahead if the cgroup is congested

From: Josef Bacik <jbacik@...com>

We noticed in testing we'd get pretty bad latency stalls under heavy
pressure because read ahead would try to do its thing while the cgroup
was under severe pressure.  If we're under this much pressure we want to
do as little IO as possible so we can still make progress on real work
if we're a throttled cgroup, so just skip readahead if our group is
under pressure.

Signed-off-by: Josef Bacik <jbacik@...com>
Acked-by: Tejun Heo <tj@...nel.org>
Acked-by: Andrew Morton <akpm@...ux-foundation.org>
---
 mm/readahead.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/readahead.c b/mm/readahead.c
index e273f0de3376..9f62b7151100 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -19,6 +19,7 @@
 #include <linux/syscalls.h>
 #include <linux/file.h>
 #include <linux/mm_inline.h>
+#include <linux/blk-cgroup.h>
 
 #include "internal.h"
 
@@ -505,6 +506,9 @@ void page_cache_sync_readahead(struct address_space *mapping,
 	if (!ra->ra_pages)
 		return;
 
+	if (blk_cgroup_congested())
+		return;
+
 	/* be dumb */
 	if (filp && (filp->f_mode & FMODE_RANDOM)) {
 		force_page_cache_readahead(mapping, filp, offset, req_size);
@@ -555,6 +559,9 @@ page_cache_async_readahead(struct address_space *mapping,
 	if (inode_read_congested(mapping->host))
 		return;
 
+	if (blk_cgroup_congested())
+		return;
+
 	/* do read-ahead */
 	ondemand_readahead(mapping, ra, filp, true, offset, req_size);
 }
-- 
2.14.3