From: Chuck Lever <cel@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: 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 09:49:55 -0500 [thread overview]
Message-ID: <02acb8f9-e60b-413c-a0d3-f1f8dda00ca3@kernel.org> (raw)
In-Reply-To: <20260107144243.GA15228@lst.de>
On 1/7/26 9:42 AM, Christoph Hellwig wrote:
> On Wed, Jan 07, 2026 at 09:36:39AM -0500, Chuck Lever wrote:
>>> 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?
>>
>> The problem, as I see it, is that the system is not providing enough
>> backpressure to slow down noisy clients, allowing them to overwhelm
>> the server's memory with UNSTABLE WRITE traffic.
>>
>> This is the same issue, IMO, that Mike's direct I/O is attempting to
>> address. Our implementation of UNSTABLE WRITE is a denial-of-service
>> vector.
>
> But how is this different from Samba or a userspace NFS server?
Well it might not be different. But at this point I don't think we know
enough about the problem to say one way or another. I'm just trying to
gather more experimental evidence about what is happening.
--
Chuck Lever
prev parent reply other threads:[~2026-01-07 14:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20251219141105.1247093-1-cel@kernel.org>
[not found] ` <20251219141105.1247093-2-cel@kernel.org>
2026-01-07 7:55 ` Christoph Hellwig
2026-01-07 14:36 ` Chuck Lever
2026-01-07 14:42 ` Christoph Hellwig
2026-01-07 14:49 ` Chuck Lever [this message]
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=02acb8f9-e60b-413c-a0d3-f1f8dda00ca3@kernel.org \
--to=cel@kernel.org \
--cc=chuck.lever@oracle.com \
--cc=hch@lst.de \
--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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox