From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>,
virtualization@lists.linux-foundation.org,
virtio-fs-list <virtio-fs@redhat.com>,
Joseph Qi <joseph.qi@linux.alibaba.com>,
linux-fsdevel@vger.kernel.org, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [Virtio-fs] [PATCH v4 0/8] fuse,virtiofs: support per-file DAX
Date: Tue, 17 Aug 2021 11:37:20 +0100 [thread overview]
Message-ID: <YRuRYJ2+hOa704sS@work-vm> (raw)
In-Reply-To: <CAJfpegvM+S5Xru3Yfc88C64mecvco=f99y-TajQBDfkLD-S8zQ@mail.gmail.com>
* Miklos Szeredi (miklos@szeredi.hu) wrote:
> On Tue, 17 Aug 2021 at 11:32, Dr. David Alan Gilbert
> <dgilbert@redhat.com> wrote:
> >
> > * Miklos Szeredi (miklos@szeredi.hu) wrote:
> > > On Tue, 17 Aug 2021 at 04:22, Jeffle Xu <jefflexu@linux.alibaba.com> wrote:
> > > >
> > > > This patchset adds support of per-file DAX for virtiofs, which is
> > > > inspired by Ira Weiny's work on ext4[1] and xfs[2].
> > >
> > > Can you please explain the background of this change in detail?
> > >
> > > Why would an admin want to enable DAX for a particular virtiofs file
> > > and not for others?
> >
> > Where we're contending on virtiofs dax cache size it makes a lot of
> > sense; it's quite expensive for us to map something into the cache
> > (especially if we push something else out), so selectively DAXing files
> > that are expected to be hot could help reduce cache churn.
>
> If this is a performance issue, it should be fixed in a way that
> doesn't require hand tuning like you suggest, I think.
I'd agree that would be nice; however:
a) It looks like other filesystems already gave something admin
selectable
b) Trying to write clever heuristics is only going to work in some
cases; being able to say 'DAX this directory' might work better in
practice.
> I'm not sure what the ext4/xfs case for per-file DAX is. Maybe that
> can help understand the virtiofs case as well.
Yep, I don't understand the case with real nvdimm hardware.
Dave
> Thanks,
> Miklos
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2021-08-17 10:37 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 2:22 [PATCH v4 0/8] fuse,virtiofs: support per-file DAX Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 1/8] fuse: add fuse_should_enable_dax() helper Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 2/8] fuse: Make DAX mount option a tri-state Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 3/8] fuse: support per-file DAX Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 4/8] fuse: negotiate if server/client supports " Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 5/8] fuse: enable " Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 6/8] fuse: mark inode DONT_CACHE when per-file DAX indication changes Jeffle Xu
2021-08-17 10:26 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-17 13:23 ` JeffleXu
2021-08-17 2:22 ` [PATCH v4 7/8] fuse: support changing per-file DAX flag inside guest Jeffle Xu
2021-08-17 2:22 ` [PATCH v4 8/8] fuse: show '-o dax=inode' option only when FUSE server supports Jeffle Xu
2021-08-17 2:23 ` [virtiofsd PATCH v4 0/4] virtiofsd: support per-file DAX Jeffle Xu
2021-08-17 2:23 ` [virtiofsd PATCH v4 1/4] virtiofsd: add .ioctl() support Jeffle Xu
2021-08-18 17:33 ` Vivek Goyal
2021-08-17 2:23 ` [virtiofsd PATCH v4 2/4] virtiofsd: expand fuse protocol to support per-file DAX Jeffle Xu
2021-08-17 2:23 ` [virtiofsd PATCH v4 3/4] virtiofsd: support per-file DAX negotiation in FUSE_INIT Jeffle Xu
2021-08-17 17:15 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-18 5:28 ` JeffleXu
2021-08-19 13:57 ` Dr. David Alan Gilbert
2021-08-18 17:30 ` Vivek Goyal
2021-08-17 2:23 ` [virtiofsd PATCH v4 4/4] virtiofsd: support per-file DAX in FUSE_LOOKUP Jeffle Xu
2021-08-17 19:00 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-18 5:46 ` JeffleXu
2021-08-19 13:08 ` Dr. David Alan Gilbert
2021-08-20 5:03 ` JeffleXu
2021-08-24 10:15 ` Greg Kurz
2021-09-08 10:34 ` JeffleXu
2021-08-17 8:06 ` [PATCH v4 0/8] fuse,virtiofs: support per-file DAX Miklos Szeredi
2021-08-17 9:32 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-08-17 10:09 ` Miklos Szeredi
2021-08-17 10:37 ` Dr. David Alan Gilbert [this message]
2021-08-17 13:08 ` JeffleXu
2021-08-17 14:11 ` Miklos Szeredi
2021-08-17 15:19 ` Vivek Goyal
2021-08-17 14:54 ` Vivek Goyal
2021-08-18 5:10 ` JeffleXu
2021-08-19 6:14 ` JeffleXu
2021-08-17 12:40 ` Vivek Goyal
2021-09-16 8:21 ` JeffleXu
2021-09-18 3:06 ` JeffleXu
2021-09-19 19:45 ` Vivek Goyal
2021-09-22 8:16 ` JeffleXu
2021-08-17 12:39 ` Vivek Goyal
2021-08-17 13:22 ` JeffleXu
2021-08-17 14:08 ` Miklos Szeredi
2021-08-18 3:39 ` JeffleXu
2021-08-18 5:08 ` Miklos Szeredi
2021-08-18 16:58 ` Vivek Goyal
2021-09-03 5:30 ` JeffleXu
2021-09-07 14:51 ` Miklos Szeredi
2021-08-17 14:57 ` Vivek Goyal
2021-08-18 5:20 ` JeffleXu
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