On Tue, Aug 7, 2018 at 6:12 PM Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote: > > Hi Kirill, > > On Tue, 07 Aug 2018 18:37:19 +0300 Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> wrote: > > > > After bitmaps of not-empty memcg shrinkers were implemented > > (see "[PATCH v9 00/17] Improve shrink_slab() scalability..." > > series, which is already in mm tree), all the evil in perf > > trace has moved from shrink_slab() to down_read_trylock(). > > As reported by Shakeel Butt: > > > > > I created 255 memcgs, 255 ext4 mounts and made each memcg create a > > > file containing few KiBs on corresponding mount. Then in a separate > > > memcg of 200 MiB limit ran a fork-bomb. > > > > > > I ran the "perf record -ag -- sleep 60" and below are the results: > > > + 47.49% fb.sh [kernel.kallsyms] [k] down_read_trylock > > > + 30.72% fb.sh [kernel.kallsyms] [k] up_read > > > + 9.51% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter > > > + 1.69% fb.sh [kernel.kallsyms] [k] shrink_node_memcg > > > + 1.35% fb.sh [kernel.kallsyms] [k] mem_cgroup_protected > > > + 1.05% fb.sh [kernel.kallsyms] [k] queued_spin_lock_slowpath > > > + 0.85% fb.sh [kernel.kallsyms] [k] _raw_spin_lock > > > + 0.78% fb.sh [kernel.kallsyms] [k] lruvec_lru_size > > > + 0.57% fb.sh [kernel.kallsyms] [k] shrink_node > > > + 0.54% fb.sh [kernel.kallsyms] [k] queue_work_on > > > + 0.46% fb.sh [kernel.kallsyms] [k] shrink_slab_memcg > > > > The patchset continues to improve shrink_slab() scalability and makes > > it lockless completely. Here are several steps for that: > > So do you have any numbers for after theses changes? > I will do the same experiment as before with these patches sometime this or next week. BTW Kirill, thanks for pushing this. regards, Shakeel
