tree d47659d651a32c53f02758c53317cefaa364e4eb
parent a2ebb6c644ca68c27e640e4a5ad8ba03ce794c38
author Josef Bacik <jbacik@fb.com> 1528987791 -0700
committer Josef Bacik <josef@toxicpanda.com> 1530625476 -0400

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>