Messages in this thread | | | From | Rik van Riel <> | Subject | Re: [PATCH 4/4] mm: zero-seek shrinkers | Date | Wed, 10 Oct 2018 01:03:50 +0000 |
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On Tue, 2018-10-09 at 14:47 -0400, Johannes Weiner wrote:
> These workloads also deal with tens of thousands of open files and > use > /proc for introspection, which ends up growing the proc_inode_cache > to > absurdly large sizes - again at the cost of valuable cache space, > which isn't a reasonable trade-off, given that proc inodes can be > re-created without involving the disk. > > This patch implements a "zero-seek" setting for shrinkers that > results > in a target ratio of 0:1 between their objects and IO-backed > caches. This allows such virtual caches to grow when memory is > available (they do cache/avoid CPU work after all), but effectively > disables them as soon as IO-backed objects are under pressure. > > It then switches the shrinkers for procfs and sysfs metadata, as well > as excess page cache shadow nodes, to the new zero-seek setting.
This patch looks like a great step in the right direction, though I do not know whether it is aggressive enough.
Given that internal slab fragmentation will prevent the slab cache from returning a slab to the VM if just one object in that slab is still in use, there may well be workloads where we should just put a hard cap on the number of freeable items these slabs, and reclaim them preemptively.
However, I do not know for sure, and this patch seems like a big improvement over what we had before, so ...
> Reported-by: Domas Mituzas <dmituzas@fb.com> > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
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