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由 Roman Gushchin 提交于
Spock reported that commit 172b06c3 ("mm: slowly shrink slabs with a relatively small number of objects") leads to a regression on his setup: periodically the majority of the pagecache is evicted without an obvious reason, while before the change the amount of free memory was balancing around the watermark. The reason behind is that the mentioned above change created some minimal background pressure on the inode cache. The problem is that if an inode is considered to be reclaimed, all belonging pagecache page are stripped, no matter how many of them are there. So, if a huge multi-gigabyte file is cached in the memory, and the goal is to reclaim only few slab objects (unused inodes), we still can eventually evict all gigabytes of the pagecache at once. The workload described by Spock has few large non-mapped files in the pagecache, so it's especially noticeable. To solve the problem let's postpone the reclaim of inodes, which have more than 1 attached page. Let's wait until the pagecache pages will be evicted naturally by scanning the corresponding LRU lists, and only then reclaim the inode structure. Link: http://lkml.kernel.org/r/20181023164302.20436-1-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com> Reported-by: NSpock <dairinin@gmail.com> Tested-by: NSpock <dairinin@gmail.com> Reviewed-by: NAndrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: <stable@vger.kernel.org> [4.19.x] Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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