Re: [PATCH 3/3] memcg: increase MEMCG_CHARGE_BATCH to 64

[Michal Hocko]

On Mon 22-08-22 11:37:30, Roman Gushchin wrote:
[...]
> I wonder only if we want to make it configurable (Idk a sysctl or maybe
> a config option) and close the topic.

I do not think this is a good idea. We have other examples where we have
outsourced internal tunning to the userspace and it has mostly proven
impractical and long term more problematic than useful (e.g.
lowmem_reserve_ratio, percpu_pagelist_high_fraction, swappiness just to
name some that come to my mind). I have seen more often these to be used
incorrectly than useful.

In this case, I guess we should consider either moving to per memcg
charge batching and see whether the pcp overhead x memcg_count is worth
that or some automagic tuning of the batch size depending on how
effectively the batch is used. Certainly a lot of room for
experimenting.

-- 
Michal Hocko
SUSE Labs