From: Christian Schoenebeck <qemu_oss@crudebyte.com>
To: qemu-devel@nongnu.org
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Venegas Munoz,
Jose Carlos" <jose.carlos.venegas.munoz@intel.com>,
"cdupontd@redhat.com" <cdupontd@redhat.com>,
virtio-fs-list <virtio-fs@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
"Shinde, Archana M" <archana.m.shinde@intel.com>,
Vivek Goyal <vgoyal@redhat.com>
Subject: Re: virtiofs vs 9p performance(Re: tools/virtiofs: Multi threading seems to hurt performance)
Date: Sun, 27 Sep 2020 14:14:43 +0200 [thread overview]
Message-ID: <66718708.HdZnNlUTFG@silver> (raw)
In-Reply-To: <20200925185147.GS2873@work-vm>
On Freitag, 25. September 2020 20:51:47 CEST Dr. David Alan Gilbert wrote:
> * Christian Schoenebeck (qemu_oss@crudebyte.com) wrote:
> > On Freitag, 25. September 2020 15:05:38 CEST Dr. David Alan Gilbert wrote:
> > > > > 9p ( mount -t 9p -o trans=virtio kernel /mnt
> > > > > -oversion=9p2000.L,cache=mmap,msize=1048576 ) test: (g=0):
> > > > > rw=randrw,
> > > >
> > > > Bottleneck ------------------------------^
> > > >
> > > > By increasing 'msize' you would encounter better 9P I/O results.
> > >
> > > OK, I thought that was bigger than the default; what number should I
> > > use?
> >
> > It depends on the underlying storage hardware. In other words: you have to
> > try increasing the 'msize' value to a point where you no longer notice a
> > negative performance impact (or almost). Which is fortunately quite easy
> > to test on>
> > guest like:
> > dd if=/dev/zero of=test.dat bs=1G count=12
> > time cat test.dat > /dev/null
> >
> > I would start with an absolute minimum msize of 10MB. I would recommend
> > something around 100MB maybe for a mechanical hard drive. With a PCIe
> > flash
> > you probably would rather pick several hundred MB or even more.
> >
> > That unpleasant 'msize' issue is a limitation of the 9p protocol: client
> > (guest) must suggest the value of msize on connection to server (host).
> > Server can only lower, but not raise it. And the client in turn obviously
> > cannot see host's storage device(s), so client is unable to pick a good
> > value by itself. So it's a suboptimal handshake issue right now.
>
> It doesn't seem to be making a vast difference here:
>
>
>
> 9p mount -t 9p -o trans=virtio kernel /mnt
> -oversion=9p2000.L,cache=mmap,msize=104857600
>
> Run status group 0 (all jobs):
> READ: bw=62.5MiB/s (65.6MB/s), 62.5MiB/s-62.5MiB/s (65.6MB/s-65.6MB/s),
> io=3070MiB (3219MB), run=49099-49099msec WRITE: bw=20.9MiB/s (21.9MB/s),
> 20.9MiB/s-20.9MiB/s (21.9MB/s-21.9MB/s), io=1026MiB (1076MB),
> run=49099-49099msec
>
> 9p mount -t 9p -o trans=virtio kernel /mnt
> -oversion=9p2000.L,cache=mmap,msize=1048576000
>
> Run status group 0 (all jobs):
> READ: bw=65.2MiB/s (68.3MB/s), 65.2MiB/s-65.2MiB/s (68.3MB/s-68.3MB/s),
> io=3070MiB (3219MB), run=47104-47104msec WRITE: bw=21.8MiB/s (22.8MB/s),
> 21.8MiB/s-21.8MiB/s (22.8MB/s-22.8MB/s), io=1026MiB (1076MB),
> run=47104-47104msec
>
>
> Dave
Is that benchmark tool honoring 'iounit' to automatically run with max. I/O
chunk sizes? What's that benchmark tool actually? And do you also see no
improvement with a simple
time cat largefile.dat > /dev/null
?
Best regards,
Christian Schoenebeck
next prev parent reply other threads:[~2020-09-27 12:16 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-18 21:34 tools/virtiofs: Multi threading seems to hurt performance Vivek Goyal
2020-09-21 8:39 ` Stefan Hajnoczi
2020-09-21 13:39 ` Vivek Goyal
2020-09-21 16:57 ` Stefan Hajnoczi
2020-09-21 8:50 ` Dr. David Alan Gilbert
2020-09-21 13:35 ` Vivek Goyal
2020-09-21 14:08 ` Daniel P. Berrangé
2020-09-21 15:32 ` Dr. David Alan Gilbert
2020-09-22 10:25 ` Dr. David Alan Gilbert
2020-09-22 17:47 ` Vivek Goyal
2020-09-24 21:33 ` Venegas Munoz, Jose Carlos
2020-09-24 22:10 ` virtiofs vs 9p performance(Re: tools/virtiofs: Multi threading seems to hurt performance) Vivek Goyal
2020-09-25 8:06 ` virtiofs vs 9p performance Christian Schoenebeck
2020-09-25 13:13 ` Vivek Goyal
2020-09-25 15:47 ` Christian Schoenebeck
2021-02-19 16:08 ` Can not set high msize with virtio-9p (Was: Re: virtiofs vs 9p performance) Vivek Goyal
2021-02-19 17:33 ` Christian Schoenebeck
2021-02-19 19:01 ` Vivek Goyal
2021-02-20 15:38 ` Christian Schoenebeck
2021-02-22 12:18 ` Greg Kurz
2021-02-22 15:08 ` Christian Schoenebeck
2021-02-22 17:11 ` Greg Kurz
2021-02-23 13:39 ` Christian Schoenebeck
2021-02-23 14:07 ` Michael S. Tsirkin
2021-02-24 15:16 ` Christian Schoenebeck
2021-02-24 15:43 ` Dominique Martinet
2021-02-26 13:49 ` Christian Schoenebeck
2021-02-27 0:03 ` Dominique Martinet
2021-03-03 14:04 ` Christian Schoenebeck
2021-03-03 14:50 ` Dominique Martinet
2021-03-05 14:57 ` Christian Schoenebeck
2020-09-25 12:41 ` virtiofs vs 9p performance(Re: tools/virtiofs: Multi threading seems to hurt performance) Dr. David Alan Gilbert
2020-09-25 13:04 ` Christian Schoenebeck
2020-09-25 13:05 ` Dr. David Alan Gilbert
2020-09-25 16:05 ` Christian Schoenebeck
2020-09-25 16:33 ` Christian Schoenebeck
2020-09-25 18:51 ` Dr. David Alan Gilbert
2020-09-27 12:14 ` Christian Schoenebeck [this message]
2020-09-29 13:03 ` Vivek Goyal
2020-09-29 13:28 ` Christian Schoenebeck
2020-09-29 13:49 ` Vivek Goyal
2020-09-29 13:59 ` Christian Schoenebeck
2020-09-29 13:17 ` Vivek Goyal
2020-09-29 13:49 ` [Virtio-fs] " Miklos Szeredi
2020-09-29 14:01 ` Vivek Goyal
2020-09-29 14:54 ` Miklos Szeredi
2020-09-29 15:28 ` Vivek Goyal
2020-09-25 12:11 ` tools/virtiofs: Multi threading seems to hurt performance Dr. David Alan Gilbert
2020-09-25 13:11 ` Vivek Goyal
2020-09-21 20:16 ` Vivek Goyal
2020-09-22 11:09 ` Dr. David Alan Gilbert
2020-09-22 22:56 ` Vivek Goyal
2020-09-23 12:50 ` [Virtio-fs] " Chirantan Ekbote
2020-09-23 12:59 ` Vivek Goyal
2020-09-25 11:35 ` Dr. David Alan Gilbert
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=66718708.HdZnNlUTFG@silver \
--to=qemu_oss@crudebyte.com \
--cc=archana.m.shinde@intel.com \
--cc=cdupontd@redhat.com \
--cc=dgilbert@redhat.com \
--cc=jose.carlos.venegas.munoz@intel.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
--cc=vgoyal@redhat.com \
--cc=virtio-fs@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).