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authorJosef Bacik <jbacik@fb.com>2018-07-03 18:15:03 +0300
committerJens Axboe <axboe@kernel.dk>2018-07-09 18:07:54 +0300
commitca47e8c72ae141587cabf3dab693f6754d8c416b (patch)
tree92d23a5608cdfa17635fe78da7b979704e61eed5
parentb351f0c76c3eb94c9ccfb68d0b23899a35e47f27 (diff)
downloadlinux-ca47e8c72ae141587cabf3dab693f6754d8c416b.tar.xz
mm: skip readahead if the cgroup is congested
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@fb.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--mm/readahead.c7
1 files changed, 7 insertions, 0 deletions
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);
}