From: Christoph Hellwig <hch@lst.de>
To: Chuck Lever <cel@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Mike Snitzer <snitzer@kernel.org>,
linux-nfs@vger.kernel.org, Chuck Lever <chuck.lever@oracle.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 1/2] NFSD: Add aggressive write throttling control
Date: Wed, 7 Jan 2026 08:55:01 +0100 [thread overview]
Message-ID: <20260107075501.GA19005@lst.de> (raw)
In-Reply-To: <20251219141105.1247093-2-cel@kernel.org>
On Fri, Dec 19, 2025 at 09:11:04AM -0500, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
>
> On NFS servers with fast network links but slow storage, clients can
> generate WRITE requests faster than the server can flush payloads to
> durable storage. This can push the server into memory exhaustion as
> dirty pages accumulate across hundreds of concurrent NFSD threads.
>
> The existing dirty page throttling (balance_dirty_pages()) uses
> per-task accounting with default ratelimits that allow each thread
> to dirty ~32 pages before throttling occurs. With many NFSD threads,
> this allows significant dirty page accumulation before any
> throttling kicks in.
What makes NFSD so special here vs say a userspace process with a bunch
of threads? Also what is the actual problem we're trying to solve?
I kinda hate having this stuff in NFSD when there's nothing specific
about nfs serving here.
next prev parent reply other threads:[~2026-01-07 7:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-19 14:11 [RFC PATCH 0/2] NFSD: Rate-limiting unstable WRITEs Chuck Lever
2025-12-19 14:11 ` [RFC PATCH 1/2] NFSD: Add aggressive write throttling control Chuck Lever
2026-01-07 7:55 ` Christoph Hellwig [this message]
2026-01-07 14:36 ` Chuck Lever
2026-01-07 14:42 ` Christoph Hellwig
2026-01-07 14:49 ` Chuck Lever
2025-12-19 14:11 ` [RFC PATCH 2/2] NFSD: Add asynchronous write throttling support Chuck Lever
2025-12-20 15:34 ` kernel test robot
2025-12-21 5:41 ` kernel test robot
2025-12-22 18:06 ` kernel test robot
2025-12-22 23:47 ` kernel test robot
2026-01-07 8:00 ` Christoph Hellwig
2026-01-07 14:42 ` Chuck Lever
2026-01-07 16:25 ` Christoph Hellwig
2026-01-07 19:40 ` Mike Snitzer
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=20260107075501.GA19005@lst.de \
--to=hch@lst.de \
--cc=cel@kernel.org \
--cc=chuck.lever@oracle.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nfs@vger.kernel.org \
--cc=snitzer@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.