On 08/17/2012 12:53 AM, Ying Han wrote: > The same patch posted two years ago at: > http://permalink.gmane.org/gmane.linux.kernel.mm/55467 > > No change since then and re-post it now mainly because it is part of the > patchset I have internally. Also, the issue that the patch addresses would > be more problematic after the patchset. > > Two changes included: > 1. only remove inode with pages in its mapping when reclaim priority hits 0. > > It helps the situation when shrink_slab() is being too agressive, it ends up > removing the inode as well as all the pages associated with the inode. > Especially when single inode has lots of pages points to it. > > The problem was observed on a production workload we run, where it has small > number of large files. Page reclaim won't blow away the inode which is pinned > by dentry which in turn is pinned by open file descriptor. But if the > application is openning and closing the fds, it has the chance to trigger > the issue. The application will experience performance hit when that happens. > > After the whole patchset, the code will call the shrinker more often by adding > shrink_slab() into target reclaim. So the performance hit will be more likely > to be observed. > > 2. avoid wrapping up when scanning inode lru. > > The target_scan_count is calculated based on the userpage lru activity, > which could be bigger than the inode lru size. avoid scanning the same > inode twice by remembering the starting point for each scan. > > Signed-off-by: Ying Han <yinghan@xxxxxxxxxx> I don't doubt the problem, but having a field in sc that is used for only one shrinker, and specifically to address a corner case, sounds like a bit of a hack. Wouldn't it be possible to make sure that such inodes are in the end of the shrinkable list, so they are effectively left for last without messing with priorities? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>