From: Johannes Weiner <hannes@cmpxchg.org>
To: Yosry Ahmed <yosryahmed@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Nhat Pham <nphamcs@gmail.com>,
Chengming Zhou <chengming.zhou@linux.dev>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 4/5] mm: zswap: remove same_filled module params
Date: Thu, 4 Apr 2024 22:35:18 -0400 [thread overview]
Message-ID: <20240405023518.GD641486@cmpxchg.org> (raw)
In-Reply-To: <20240405013547.1859126-5-yosryahmed@google.com>
On Fri, Apr 05, 2024 at 01:35:46AM +0000, Yosry Ahmed wrote:
> These knobs offer more fine-grained control to userspace than needed and
> directly expose/influence kernel implementation; remove them.
>
> For disabling same_filled handling, there is no logical reason to refuse
> storing same-filled pages more efficiently and opt for compression.
> Scanning pages for patterns may be an argument, but the page contents
> will be read into the CPU cache anyway during compression. Also,
> removing the same_filled handling code does not move the needle
> significantly in terms of performance anyway [1].
>
> For disabling non_same_filled handling, it was added when the compressed
> pages in zswap were not being properly charged to memcgs, as workloads
> could escape the accounting with compression [2]. This is no longer the
> case after commit f4840ccfca25 ("zswap: memcg accounting"), and using
> zswap without compression does not make much sense.
>
> [1]https://lore.kernel.org/lkml/CAJD7tkaySFP2hBQw4pnZHJJwe3bMdjJ1t9VC2VJd=khn1_TXvA@mail.gmail.com/
> [2]https://lore.kernel.org/lkml/19d5cdee-2868-41bd-83d5-6da75d72e940@maciej.szmigiero.name/
>
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2024-04-05 2:35 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-05 1:35 [PATCH v1 0/5] zswap same-filled and limit checking cleanups Yosry Ahmed
2024-04-05 1:35 ` [PATCH v1 1/5] mm: zswap: always shrink in zswap_store() if zswap_pool_reached_full Yosry Ahmed
2024-04-05 1:35 ` [PATCH v1 2/5] mm: zswap: refactor limit checking from zswap_store() Yosry Ahmed
2024-04-05 2:44 ` Johannes Weiner
2024-04-05 4:15 ` Yosry Ahmed
2024-04-05 1:35 ` [PATCH v1 3/5] mm: zswap: move more same-filled pages checks outside of zswap_store() Yosry Ahmed
2024-04-05 2:34 ` Johannes Weiner
2024-04-05 1:35 ` [PATCH v1 4/5] mm: zswap: remove same_filled module params Yosry Ahmed
2024-04-05 2:35 ` Johannes Weiner [this message]
2024-04-05 1:35 ` [PATCH v1 5/5] mm: zswap: do not check the global limit for same-filled pages Yosry Ahmed
2024-04-05 2:54 ` Johannes Weiner
2024-04-05 4:19 ` Yosry Ahmed
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=20240405023518.GD641486@cmpxchg.org \
--to=hannes@cmpxchg.org \
--cc=akpm@linux-foundation.org \
--cc=chengming.zhou@linux.dev \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=nphamcs@gmail.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