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@xxxxxx> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Reviewed-by: Rik van Riel <riel@xxxxxxxxxxx>
