Re: [Xen-devel] blkif shared ring

To:	"Samvel Yuri" <samvelox@xxxxxxxxx>
Subject:	Re: [Xen-devel] blkif shared ring
From:	"Geoffrey Lefebvre" <geoffrey@xxxxxxxxx>
Date:	Tue, 18 Nov 2008 17:16:21 -0800
Cc:	Dutch Meyer <dmeyer@xxxxxxxxx>, Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Andrew Warfield <andy@xxxxxxxxx>
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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

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Re: [Xen-devel] blkif shared ring