linux-kernel - Re: [PATCH] mm/vmscan: fix infinite loop in drop_slab

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Date:   Tue, 8 Sep 2020 16:09:45 +0100
From:   Chris Down <chris@...isdown.name>
To:     zangchunxin@...edance.com
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: Re: [PATCH] mm/vmscan: fix infinite loop in drop_slab_node

drop_caches by its very nature can be extremely performance intensive -- if 
someone wants to abort after trying too long, they can just send a 
TASK_KILLABLE signal, no? If exiting the loop and returning to usermode doesn't 
reliably work when doing that, then _that's_ something to improve, but this 
looks premature to me until that's demonstrated not to work.

zangchunxin@...edance.com writes:
>In one drop caches action, only traverse memcg once maybe is better.
>If user need more memory, they can do drop caches again.

Can you please provide some measurements of the difference in reclamation in 
practice?