On Fri, Apr 15, 2022 at 05:27:51PM -0700, Roman Gushchin wrote: > There are 50+ different shrinkers in the kernel, many with their own bells and > whistles. Under the memory pressure the kernel applies some pressure on each of > them in the order of which they were created/registered in the system. Some > of them can contain only few objects, some can be quite large. Some can be > effective at reclaiming memory, some not. > > The only existing debugging mechanism is a couple of tracepoints in > do_shrink_slab(): mm_shrink_slab_start and mm_shrink_slab_end. They aren't > covering everything though: shrinkers which report 0 objects will never show up, > there is no support for memcg-aware shrinkers. Shrinkers are identified by their > scan function, which is not always enough (e.g. hard to guess which super > block's shrinker it is having only "super_cache_scan"). They are a passive > mechanism: there is no way to call into counting and scanning of an individual > shrinker and profile it. > > To provide a better visibility and debug options for memory shrinkers > this patchset introduces a /sys/kernel/shrinker interface, to some extent > similar to /sys/kernel/slab. Wouldn't debugfs better fit the purpose of shrinker debugging? -- Sincerely yours, Mike.
