From: Josef Bacik Date: Tue, 3 Jul 2018 15:15:03 +0000 (-0400) Subject: mm: skip readahead if the cgroup is congested X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ca47e8c72ae141587cabf3dab693f6754d8c416b;p=linux.git 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 Acked-by: Tejun Heo Acked-by: Andrew Morton Signed-off-by: Jens Axboe --- diff --git a/mm/readahead.c b/mm/readahead.c index e273f0de33769..9f62b71511001 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -19,6 +19,7 @@ #include #include #include +#include #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); }