Re: [net] 4890b686f4: netperf.Throughput_Mbps -69.4% regression

[Roman Gushchin]

On Mon, Jun 27, 2022 at 09:48:01AM -0700, Shakeel Butt wrote:
> On Mon, Jun 27, 2022 at 9:26 AM Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
> >
> [...]
> > >
> >
> > I simply did the following and got much better results.
> >
> > But I am not sure if updates to ->usage are really needed that often...
> 
> I suspect we need to improve the per-cpu memcg stock usage here. Were
> the updates mostly from uncharge path or charge path or that's
> irrelevant?
> 
> I think doing full drain (i.e. drain_stock()) within __refill_stock()
> when the local cache is larger than MEMCG_CHARGE_BATCH is not best.
> Rather we should always keep at least MEMCG_CHARGE_BATCH for such
> scenarios.

+1, really good point.