Re: [Xen-devel] blkif shared ring

[Samvel Yuri <samvelox@xxxxxxxxx>]

hello Geoffrey-

Ahh, so Parallax project just do multi-page ring (and not entirely another set of shared ring). I
am going to try 4 * PAGE_SIZE and see whether the box stays alive. Were the patches self
contained in blkfront & blkback? If possible a pointer to blkfront & blkback will be useful.

thanks for you reply,
Sameer

thanks,
~Sam

---

From: Geoffrey Lefebvre <geoffrey@xxxxxxxxx>
To: Samvel Yuri <samvelox@xxxxxxxxx>
Cc: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>; Dutch Meyer <dmeyer@xxxxxxxxx>; Andrew Warfield <andy@xxxxxxxxx>
Sent: Tuesday, November 18, 2008 5:16:21 PM
Subject: Re: [Xen-devel] blkif shared ring

On Tue, Nov 18, 2008 at 3:49 PM, Samvel Yuri <samvelox@xxxxxxxxx> wrote:
>
> hi Samuel-
>
> Would you please explain what do you mean by "using the whole buffer page"?
>
> Parallax (project of University of British Columbia) modified XEN by
> allocating an
> additional shared ring page in the blkback driver. Probably one of options?
>

Hi,

Regarding Parallax, we added support for multi-page ring to increase
the throughput of a guest block device when using an iscsi filer as a
backend. The single page ring is enough to saturate a standard SATA
drive but we got a noticeable performance increase (from 65 to a
105MBps I think) when we doubled the ring size with the iscsi backend.

I remember seeing multi-page ring patches for mini-os and fs-back from
Samuel. Is there a plan to generalize these patches to
blkfront/back/tap?

We had patches for blkfront, blkback and blktap. The size of the ring
was a compile time option for blkfront. The patches are pretty old
(3.1 I think) but could probably be refreshed without too much effort.

geoffrey

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel