From: Rick Macklem <rick.macklem@gmail.com>
To: Cedric Blancher <cedric.blancher@gmail.com>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
freebsd-hackers@freebsd.org
Subject: Re: Increase FreeBSD NFSv4 nfsd buffer size? Re: Increase default NFSv4 server size "max_block_size" to 4MB
Date: Tue, 12 May 2026 16:02:16 -0700 [thread overview]
Message-ID: <CAM5tNy76P-1Q2EhJ4zXUtc=EwRYgke8ZqJEYvM=sRyY77rxHLA@mail.gmail.com> (raw)
In-Reply-To: <CALXu0UckL3YYXVLz5Qn0shoZ+TU8uOxRy2FCpL5mAhLniinJyg@mail.gmail.com>
On Tue, May 12, 2026 at 6:18 AM Cedric Blancher
<cedric.blancher@gmail.com> wrote:
>
> On Tue, 17 Mar 2026 at 00:35, Rick Macklem <rick.macklem@gmail.com> wrote:
> >
> > On Mon, Mar 16, 2026 at 5:41 AM 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?
> > Although it has not seen much testing, it is possible to do a > 1Mbyte NFSv4
> > mount in FreeBSD.
> > For a 2Mbyte mount, (the only size > 1Mbyte I've tried) the settings would be..
> > In /boot/loader.conf
> > kern.maxphys=2097152
> > vfs.maxbcachebuf=2097152
> >
> > and in /etc/sysctl.conf
> > kern.ipc.maxsockbuf=9455616
> >
> > Then a mount will use 2Mbytes if the server supports it.
>
> How can I verify that the FreeBSD NFSv4 nfsd now uses 2M for NFS buffers?
The default is 128K. (You can see what it is via "sysctl vfs.nfsd.srvmaxio".)
With "main", you can increase that up to 4M by putting
nfs_server_maxio=N (where N can be up to 4194304 for "main" and 1048576 for 15)
- adding an entry in /etc/sysctl.conf for a larger value for kern.ipc.maxsockbuf
(It will tell you the recommended minimum setting if you boot after
putting nfs_server_maxio=N in /etc/rc.conf.)
rick
>
> Ced
> --
> Cedric Blancher <cedric.blancher@gmail.com>
> [https://plus.google.com/u/0/+CedricBlancher/]
> Institute Pasteur
next prev parent reply other threads:[~2026-05-12 23:02 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
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 [this message]
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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