tree 92d23a5608cdfa17635fe78da7b979704e61eed5
parent b351f0c76c3eb94c9ccfb68d0b23899a35e47f27
author Josef Bacik <jbacik@fb.com> 1530630903 -0400
committer Jens Axboe <axboe@kernel.dk> 1531148874 -0600

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>