Date: Fri, 17 Jan 2025 16:03:08 -0800 From: Rick Macklem <rick.macklem@gmail.com> To: Alan Somers <asomers@freebsd.org> Cc: Cedric Blancher <cedric.blancher@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: WRITE_SAME support in FreeBSD nfsd NFSv4.1 mode? Message-ID: <CAM5tNy4DmgPoKWRONv86v%2BOxEjX0bK4--tcXnWmtOQN96aaaQA@mail.gmail.com> In-Reply-To: <CAOtMX2jVjMsDdE_E=kZg2OHUbhq=XzRuu1YEowyQXkyg%2Bx7qXg@mail.gmail.com> References: <CAAvCNcD1CziGxmgyzyWix5ADsDXRpkbFUM32H9nEji9kR%2BVc-Q@mail.gmail.com> <CAOtMX2i29F8NU493v81ggsdcprr7iifuD1aivaxsULxZrYt1tA@mail.gmail.com> <CALXu0UcP5WR_gV000akarzDxGap70jJwNaf7_BgKgVVU0S2bzg@mail.gmail.com> <CAOtMX2jVjMsDdE_E=kZg2OHUbhq=XzRuu1YEowyQXkyg%2Bx7qXg@mail.gmail.com>
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On Sun, Jan 12, 2025 at 1:18=E2=80=AFPM Alan Somers <asomers@freebsd.org> w= rote: > > On Sun, Jan 12, 2025 at 12:23=E2=80=AFAM 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=E2=80=AFPM Dan Shelton <dan.f.shelton@gma= il.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-winioct= l-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 ne= ed. rick >
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