On Fri, Apr 9, 2021 at 9:35 AM Masayoshi Mizuma <msys.mizuma@xxxxxxxxx> wrote:
>
[...]
> > Can you please explain how to read these numbers? Or at least put a %
> > regression.
>
> Let me summarize them here.
> The total duration ('total' column above) of each system call is as follows
> if v5.8 is assumed as 100%:
>
> - sendto:
> - v5.8 100%
> - v5.9 128%
> - v5.12-rc6 116%
>
> - revfrom:
> - v5.8 100%
> - v5.9 114%
> - v5.12-rc6 108%
>
Thanks, that is helpful. Most probably the improvement of 5.12 from
5.9 is due to 3de7d4f25a7438f ("mm: memcg/slab: optimize objcg stock
draining").
[...]
> >
> > One idea would be to increase MEMCG_CHARGE_BATCH.
>
> Thank you for the idea! It's hard-corded as 32 now, so I'm wondering it may be
> a good idea to make MEMCG_CHARGE_BATCH tunable from a kernel parameter or something.
>
Can you rerun the benchmark with MEMCG_CHARGE_BATCH equal 64UL?
I think with memcg stats moving to rstat, the stat accuracy is not an
issue if we increase MEMCG_CHARGE_BATCH to 64UL. Not sure if we want
this to be tuneable but most probably we do want this to be sync'ed
with SWAP_CLUSTER_MAX.
