From 534f7eff9239c1b0af852fc33f5af2b62c00eddf Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 16 Aug 2024 10:40:38 +0930 Subject: btrfs: only enable extent map shrinker for DEBUG builds Although there are several patches improving the extent map shrinker, there are still reports of too frequent shrinker behavior, taking too much CPU for the kswapd process. So let's only enable extent shrinker for now, until we got more comprehensive understanding and a better solution. Link: https://lore.kernel.org/linux-btrfs/3df4acd616a07ef4d2dc6bad668701504b412ffc.camel@intelfx.name/ Link: https://lore.kernel.org/linux-btrfs/c30fd6b3-ca7a-4759-8a53-d42878bf84f7@gmail.com/ Fixes: 956a17d9d050 ("btrfs: add a shrinker for extent maps") CC: stable@vger.kernel.org # 6.10+ Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/super.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 11044e9e2cb1..98fa0f382480 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2402,7 +2402,13 @@ static long btrfs_nr_cached_objects(struct super_block *sb, struct shrink_contro trace_btrfs_extent_map_shrinker_count(fs_info, nr); - return nr; + /* + * Only report the real number for DEBUG builds, as there are reports of + * serious performance degradation caused by too frequent shrinks. + */ + if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) + return nr; + return 0; } static long btrfs_free_cached_objects(struct super_block *sb, struct shrink_control *sc) -- cgit v1.2.3-58-ga151