Re: [PATCH V7 1/2] cgroup/rstat: Avoid thundering herd problem by kswapd across NUMA nodes

[Shakeel Butt]

On Fri, Jul 19, 2024 at 09:54:41AM GMT, Jesper Dangaard Brouer wrote:
> 
> 
> On 19/07/2024 02.40, Shakeel Butt wrote:
> > Hi Jesper,
> > 
> > On Wed, Jul 17, 2024 at 06:36:28PM GMT, Jesper Dangaard Brouer wrote:
> > > 
> > [...]
> > > 
> > > 
> > > Looking at the production numbers for the time the lock is held for level 0:
> > > 
> > > @locked_time_level[0]:
> > > [4M, 8M)     623 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@               |
> > > [8M, 16M)    860 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
> > > [16M, 32M)   295 |@@@@@@@@@@@@@@@@@                                   |
> > > [32M, 64M)   275 |@@@@@@@@@@@@@@@@                                    |
> > > 
> > 
> > Is it possible to get the above histogram for other levels as well?
> 
> Data from other levels available in [1]:
>  [1]
> https://lore.kernel.org/all/8c123882-a5c5-409a-938b-cb5aec9b9ab5@xxxxxxxxxx/
> 
> IMHO the data shows we will get most out of skipping level-0 root-cgroup
> flushes.
> 

Thanks a lot of the data. Are all or most of these locked_time_level[0]
from kswapds? This just motivates me to strongly push the ratelimited
flush patch of mine (which would be orthogonal to your patch series).

Shakeel