Re: [RFC PATCH 0/2] mm: multi-gen LRU: working set extensions

[Michal Koutný]

On Wed, Dec 14, 2022 at 02:51:21PM -0800, Yuanchu Xie <yuanchu@xxxxxxxxxx> wrote:
> that's frequently used. The only missing pieces between MGLRU
> generations and working set estimation are a consistent aging cadence
> and an interface; we introduce the two additions.
> 
> Periodic aging
> ======
> MGLRU Aging is currently driven by reclaim, so the amount of time
> between generations is non-deterministic. With memcgs being aged
> regularly, MGLRU generations become time-based working set information.

Is this periodic aging specific to memcgs? IOW, periodic aging isn't
needed without memcgs (~with root only)
(Perhaps similar question to Aneeh's.)

> Use case: proactive reclaimer
> ======
> The proactive reclaimer sets the aging interval, and periodically reads
> the page idle age stats, forming a working set estimation, which it then
> calculates an amount to write to memory.reclaim.
> 
> With the page idle age stats, a proactive reclaimer could calculate a
> precise amount of memory to reclaim without continuously probing and
> inducing reclaim.

Could the aging be also made per-memcg? (Similar to memory.reclaim,
possibly without the new kthread (if global reclaim's aging is enough).)

Thanks,
Michal

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