From: Vlastimil Babka <vbabka@suse.cz>
To: Chris Down <chris@chrisdown.name>, zangchunxin@bytedance.com
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH] mm/vmscan: fix infinite loop in drop_slab_node
Date: Tue, 8 Sep 2020 17:42:05 +0200 [thread overview]
Message-ID: <07c6ebf1-e2b3-11a2-538f-4ac542a4373b@suse.cz> (raw)
In-Reply-To: <20200908150945.GA1301981@chrisdown.name>
On 9/8/20 5:09 PM, Chris Down wrote:
> 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.
Hm there might be existings scripts (even though I dislike those) running
drop_caches periodically, and they are currently not set up to be killed, so one
day it might surprise someone. Dropping should be a one-time event, not a
continual reclaim.
Maybe we could be a bit smarter and e.g. double the threshold currently
hardcoded as "10" with each iteration?
> zangchunxin@bytedance.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?
>
next prev parent reply other threads:[~2020-09-08 15:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-08 14:24 zangchunxin
2020-09-08 15:09 ` Chris Down
2020-09-08 15:42 ` Vlastimil Babka [this message]
2020-09-08 17:55 ` Chris Down
2020-09-09 4:19 ` [External] " Muchun Song
2020-09-09 9:59 ` Chris Down
2020-09-09 12:10 ` Muchun Song
2020-09-09 15:26 ` 臧春鑫
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=07c6ebf1-e2b3-11a2-538f-4ac542a4373b@suse.cz \
--to=vbabka@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=chris@chrisdown.name \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=songmuchun@bytedance.com \
--cc=zangchunxin@bytedance.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox