Re: WRITE_SAME support in FreeBSD nfsd NFSv4.1 mode?

On Fri, Jan 17, 2025 at 5:03 PM Rick Macklem <rick.macklem@gmail.com> wrote:
>
> On Sun, Jan 12, 2025 at 1:18 PM Alan Somers <asomers@freebsd.org> wrote:
> >
> > On Sun, Jan 12, 2025 at 12:23 AM Cedric Blancher
> > <cedric.blancher@gmail.com> wrote:
> > >
> > > On Fri, 10 Jan 2025 at 16:02, Alan Somers <asomers@freebsd.org> wrote:
> > > >
> > > > On Thu, Jan 9, 2025 at 5:31 PM Dan Shelton <dan.f.shelton@gmail.com> wrote:
> > > > >
> > > > > Hello!
> > > > >
> > > > > Does FreeBSD nfsd support the WRITE_SAME request in NFSv4.1 mode?
> > > > >
> > > > > Dan
> > > > > --
> > > > > Dan Shelton - Cluster Specialist Win/Lin/Bsd
> > > >
> > > > Out of curiosity, what is your use case?
> > >
> > > As discussed in the linux-nfs@ list, is a typical "big data" and
> > > database accelerator, for example fast pattern fill (1 WRITE_SAME
> > > command over the write, compared to <n> commands with data block,
> > > where <n> is typically > 200 average), or just zero fill for blocks.
> > > It's basically reducing network traffic dramatically.
> > >
> > > Windows SMB 3.0 already supports that, and is a main selling point for
> > > M$ to keep database people on the W$ platform. They even added several
> > > Windows syscalls like
> > > https://learn.microsoft.com/en-us/windows/win32/api/winioctl/ni-winioctl-fsctl_set_zero_data
> > >
> > > Ced
> >
> > I understand why WRITE SAME would greatly reduce network traffic
> > compared to writing the same data n times.  But my question is, what
> > real application requires that, where the data isn't simply all-zeros?
> >  Are there database operations that require writing the same non-zero
> > pattern to multiple blocks?
> You might find the discussion on the linux-nfs@vger.kernel.org
> mailing list interesting.
> It is under this subject line:
> [LSF/MM/BPF TOPIC] Implementing the NFS v4.2 WRITE_SAME operation: VFS
> or NFS ioctl() ?
>
> Although there is no consensus, it seems to me that there is not a lot
> of use for anything beyond zeroing blocks.
> Unfortunately a WRITE_SAME implementation needs to do a lot more
> that zero blocks.
>
> I am holding off on any server implementation until there is an apparent need.

That sounds wise.