This reverts commit 0388536ac29104a478c79b3869541524caec28eb. Proactive reclaim on the root cgroup is 10x slower after this patch when MGLRU is enabled, and completion times for proactive reclaim on much smaller non-root cgroups take ~30% longer (with or without MGLRU). With root reclaim before the patch, I observe average reclaim rates of ~70k pages/sec before try_to_free_mem_cgroup_pages starts to fail and the nr_retries counter starts to decrement, eventually ending the proactive reclaim attempt. After the patch the reclaim rate is consistently ~6.6k pages/sec due to the reduced nr_pages value causing scan aborts as soon as SWAP_CLUSTER_MAX pages are reclaimed. The proactive reclaim doesn't complete after several minutes because try_to_free_mem_cgroup_pages is still capable of reclaiming pages in tiny SWAP_CLUSTER_MAX page chunks and nr_retries is never decremented. The docs for memory.reclaim say, "the kernel can over or under reclaim from the target cgroup" which this patch was trying to fix. Revert it until a less costly solution is found. Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx> --- mm/memcontrol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e4c8735e7c85..cee536c97151 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6956,8 +6956,8 @@ static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf, lru_add_drain_all(); reclaimed = try_to_free_mem_cgroup_pages(memcg, - min(nr_to_reclaim - nr_reclaimed, SWAP_CLUSTER_MAX), - GFP_KERNEL, reclaim_options); + nr_to_reclaim - nr_reclaimed, + GFP_KERNEL, reclaim_options); if (!reclaimed && !nr_retries--) return -EAGAIN; -- 2.43.0.429.g432eaa2c6b-goog
