On 08.08.2018 08:39, Shakeel Butt wrote: > 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. Thanks, Shakeel! > BTW Kirill, thanks for pushing this. > > regards, > Shakeel >
