Hi Shakeel,
On Mon, Sep 13, 2021 at 01:13:57PM -0700, Shakeel Butt wrote:
> On Mon, Sep 13, 2021 at 1:10 PM Tejun Heo <tj@xxxxxxxxxx> wrote:
> >
> > On Mon, Sep 13, 2021 at 01:09:11PM -0700, Shakeel Butt wrote:
> > > Thanks a lot for the explanation. Are there any concerns to call
> > > cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup) in system_wq?
> > > This will be called every 2 seconds, so, we can assume the updated
> > > tree would be small most of the time.
> >
> > I can't think of a reason why this would be problematic.
> >
>
> Thanks again.
>
> Feng, is it possible to re-run these benchmarks with
> queue_work(system_wq) instead of queue_work(system_unbound_wq)?
I just run the patch twice, and there was no obvious change, the
hotspot is still the spinlock.
Thanks,
Feng
$git-diff aa48e47e
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4d8c9af..fa9cae9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -683,7 +683,7 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
/* Update lruvec */
__this_cpu_add(pn->lruvec_stats_percpu->state[idx], val);
if (!(__this_cpu_inc_return(stats_flush_threshold) % MEMCG_CHARGE_BATCH))
- queue_work(system_unbound_wq, &stats_flush_work);
+ queue_work(system_wq, &stats_flush_work);
}
7e1c0d6f58207e7e aa48e47e3906c332eaf1e5d7b58 1638eee6432c1a5175685a7945a
---------------- --------------------------- ---------------------------
\ | \ | \
648.62 +243.0% 2224 ± 3% +246.1% 2244 aim7.cpu
588139 -13.4% 509421 -13.5% 508738 aim7.jobs-per-min
196.05 -13.4% 169.81 -13.5% 169.58 aim7.jobs-per-min-per-task
3.93 ± 3% +62.8 66.70 +63.4 67.37 pp.child.native_queued_spin_lock_slowpath
3.96 ± 4% +62.8 66.76 +63.5 67.46 pp.child._raw_spin_lock_irqsave
3.66 ± 5% +62.9 66.54 +63.6 67.22 pp.child.lock_page_lruvec_irqsave
0.00 +0.1 0.10 ± 5% +0.1 0.09 pp.self.queue_work_on
0.00 +0.2 0.18 ± 5% +0.2 0.22 pp.self.cgroup_rstat_flush_locked
0.00 +0.6 0.60 ± 7% +0.7 0.72 ± 3% pp.self.mem_cgroup_css_rstat_flush
0.19 +0.7 0.86 ± 5% +0.7 0.84 ± 4% pp.self.cgroup_rstat_updated
3.92 ± 3% +62.8 66.70 +63.4 67.37 pp.self.native_queued_spin_lock_slowpath
