From: Johannes Weiner <hannes@cmpxchg.org>
To: 贺中坤 <hezhongkun.hzk@bytedance.com>
Cc: Nhat Pham <nphamcs@gmail.com>,
akpm@linux-foundation.org, yosryahmed@google.com,
sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [External] Re: [RFC PATCH] zswap: add writeback_time_threshold interface to shrink zswap pool
Date: Thu, 12 Oct 2023 10:22:03 -0400 [thread overview]
Message-ID: <20231012142203.GB470544@cmpxchg.org> (raw)
In-Reply-To: <CACSyD1N6PPJCJ6TCTGijRKGEf2bGm+3mBLfr=DwCKgy+7-PBEw@mail.gmail.com>
On Thu, Oct 12, 2023 at 10:13:16PM +0800, 贺中坤 wrote:
> Hi Nhat, thanks for your detailed reply.
>
> > We're currently trying to solve this exact problem. Our approach is to
> > add a shrinker that automatically shrinks the size of the zswap pool:
> >
> > https://lore.kernel.org/lkml/20230919171447.2712746-1-nphamcs@gmail.com/
> >
> > It is triggered on memory-pressure, and can perform reclaim in a
> > workload-specific manner.
> >
> > I'm currently working on v3 of this patch series, but in the meantime,
> > could you take a look and see if it will address your issues as well?
> >
> > Comments and suggestions are always welcome, of course :)
> >
>
> Thanks, I've seen both patches. But we hope to be able to reclaim memory
> in advance, regardless of memory pressure, like memory.reclaim in memcg,
> so we can offload memory in different tiers.
Can you use memory.reclaim itself for that? With Nhat's shrinker, it
should move the whole pipeline (LRU -> zswap -> swap).
> Thanks for your review，we should update the store time when it was loaded.
> But it confused me, there are two copies of the same page in memory
> (compressed and uncompressed) after faulting in a page from zswap if
> 'zswap_exclusive_loads_enabled' was disabled. I didn't notice any difference
> when turning that option on or off because the frontswap_ops has been removed
> and there is no frontswap_map anymore. Sorry, am I missing something?
In many instances, swapins already free the swap slot through the
generic swap code (see should_try_to_free_swap()). It matters for
shared pages, or for swapcaching read-only data when swap isn't full -
it could be that isn't the case in your tests.
next prev parent reply other threads:[~2023-10-12 14:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-11 5:11 Zhongkun He
2023-10-11 19:36 ` Nhat Pham
2023-10-12 14:13 ` [External] " 贺中坤
2023-10-12 14:22 ` Johannes Weiner [this message]
2023-10-13 12:59 ` 贺中坤
2023-10-12 18:08 ` Nhat Pham
2023-10-13 13:38 ` 贺中坤
2023-10-13 2:46 ` Yosry Ahmed
2023-10-13 14:02 ` [External] " 贺中坤
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=20231012142203.GB470544@cmpxchg.org \
--to=hannes@cmpxchg.org \
--cc=akpm@linux-foundation.org \
--cc=ddstreet@ieee.org \
--cc=hezhongkun.hzk@bytedance.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=nphamcs@gmail.com \
--cc=sjenning@redhat.com \
--cc=vitaly.wool@konsulko.com \
--cc=yosryahmed@google.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