On Thu, 2010-05-27 at 13:32 -0700, Andrew Morton wrote: > On Tue, 25 May 2010 18:53:03 +1000 > Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > > This series reworks the filesystem shrinkers. We currently have a > > set of issues with the current filesystem shrinkers: > > > > 1. There is an dependency between dentry and inode cache > > shrinking that is only implicitly defined by the order of > > shrinker registration. > > 2. The shrinkers need to walk the superblock list and pin > > the superblock to avoid unmount races with the sb going > > away. > > 3. The dentry cache uses per-superblock LRUs and proportions > > reclaim between all the superblocks which means we are > > doing breadth based reclaim. This means we touch every > > superblock for every shrinker call, and may only reclaim > > a single dentry at a time from a given superblock. > > 4. The inode cache has a global LRU, so it has different > > reclaim patterns to the dentry cache, despite the fact > > that the dentry cache is generally the only thing that > > pins inodes in memory. > > 5. Filesystems need to register their own shrinkers for > > caches and can't co-ordinate them with the dentry and > > inode cache shrinkers. > > Nice description, but... it never actually told us what the benefit of > the changes are. Presumably some undescribed workload had some > undescribed user-visible problem. But what was that workload, and what > was the user-visible problem, and how does the patch affect all this? For UBIFS it wwill give a benefit in terms of simpler UBIFS code - we now have to keep our own list of UBIFS superblocks, provide locking for it, and maintain. This is just extra burden. So the item 2 above will be useful for UBIFS. -- Best Regards, Artem Bityutskiy (Артём Битюцкий) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
