Re: Increase default NFSv4 server size "max_block_size" to 4MB

[Mike Snitzer <snitzer@kernel.org>]

On Tue, Mar 17, 2026 at 09:51:23AM -0400, Anna Schumaker wrote:
> 
> 
> On Mon, Mar 16, 2026, at 8:39 AM, Chuck Lever 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?
> 
> The NFS client would need a code change to support >1MB sizes. I
> spent some time playing around with 4MB yesterday and it passed
> all my tests.

Is this something you'd be open to posting to the list?

Would be interested to see how 'git clone' improves with it.

Thanks,
Mike