From: Roland Mainz <roland.mainz@nrubsig.org>
To: Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: Increase default NFSv4 server size "max_block_size" to 4MB
Date: Mon, 16 Mar 2026 15:40:43 +0100 [thread overview]
Message-ID: <CAKAoaQkFfQ0LvnmfMoXD8RJfwhnqOZy2c--wLoANfMdPLyqP2g@mail.gmail.com> (raw)
In-Reply-To: <5acaa8e7-0691-4cbd-b501-c26831a7be81@app.fastmail.com>
On Mon, Mar 16, 2026 at 1:39 PM Chuck Lever <cel@kernel.org> wrote:
> On Mon, Mar 16, 2026, at 3:51 AM, Cedric Blancher wrote:
> > As debated a while ago, can the default NFSv4 server size for
> > "max_block_size" be increased to 4MB, please?
>
> There is an administrative setting to raise this limit for
> recent versions of the kernel. Can you report your experience
> when you raise the limit? Hiccups, performance issues, etc? I
> would kind of like this exercise to be data-driven.
>
> What is still unknown to me is which NFS client implementations
> can support 4MB or 8MB. Without client support, an increase in
> the default in NFSD doesn't mean anything. Rick, Anna, Roland?
Linux 6.17 NFS server:
$ service nfs-server stop
$ printf '%d\n' $((4*1024*1024)) >/proc/fs/nfsd/max_block_size
$ service nfs-server start
Mounting the filesystem with ms-nfs41-client and compiling Cygwin
bash.exe and ms-nfs41-client with Visual Studio etc. works fine...
... and I verified that |FATTR4_MAXREAD| and |FATTR4_MAXWRITE| have
the value |4194304| as expected.
I didn't make any benchmarks yet, but quick observation shows that
cloning a git from a git bundle on the same NFSv4.2 filesystem is up
from 8.1MB/s to 8.8MB/s.
----
Bye,
Roland
--
__ . . __
(o.\ \/ /.o) roland.mainz@nrubsig.org
\__\/\/__/ MPEG specialist, C&&JAVA&&Sun&&Unix programmer
/O /==\ O\ TEL +49 641 3992797
(;O/ \/ \O;)
next prev parent reply other threads:[~2026-03-16 14:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 7:51 Increase default NFSv4 server size "max_block_size" to 4MB Cedric Blancher
2026-03-16 12:39 ` Chuck Lever
2026-03-16 14:40 ` Roland Mainz [this message]
2026-03-16 23:35 ` Rick Macklem
2026-05-12 13:18 ` Increase FreeBSD NFSv4 nfsd buffer size? " Cedric Blancher
2026-05-12 23:02 ` Rick Macklem
2026-05-13 8:37 ` Cedric Blancher
2026-05-13 23:38 ` Rick Macklem
2026-05-14 22:39 ` Rick Macklem
2026-05-14 22:52 ` vermaden
2026-05-14 23:49 ` Rick Macklem
2026-03-17 13:51 ` Anna Schumaker
2026-03-30 18:46 ` Mike Snitzer
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