Re: [RESEND] [PATCH] readahead:add blk_run_backing_dev

[Vladislav Bolkhovitin]

Wu Fengguang, on 06/29/2009 06:51 PM wrote:
> On Mon, Jun 29, 2009 at 10:43:48PM +0800, Ronald Moesbergen wrote:
> > 2009/6/29 Wu Fengguang <fengguang.wu@xxxxxxxxx>:
> > > On Mon, Jun 29, 2009 at 09:13:27PM +0800, Wu Fengguang wrote:
> > > > On Mon, Jun 29, 2009 at 09:04:57PM +0800, Vladislav Bolkhovitin wrote:
> > > > > Wu Fengguang, on 06/29/2009 04:54 PM wrote:
> > > > > > Why not 2.6.30? :)
> > > > > We started with 2.6.29, so why not complete with it (to save additional
> > > > > Ronald's effort to move on 2.6.30)?
> > > > OK, that's fair enough.
> > > btw, I backported the 2.6.31 context readahead patches to 2.6.29, just
> > > in case it will help the SCST performance.
> > >
> > > Ronald, if you run context readahead, please make sure that the server
> > > side readahead size is bigger than the client side readahead size.
> > I tried this patch on a vanilla kernel and no other patches applied,
> > but it does not seem to help. The iSCSI throughput does not go above
> > 60MB/s. (1GB in 17 seconds). I have tried several readahead settings
> > from 128KB up to 4MB and kept the server readahead at twice the client
> > readahead, but it never comes above 60MB/s. This is using SCST on the
>
> OK, thanks for the tests anyway!
>
> > serverside and openiscsi on the client. I get much better throughput
> > (90 MB/s) when using the patches supplied with SCST, together with the
>
> What do you mean by "patches supplied with SCST"?

Ronald means io_context patch 
(http://scst.svn.sourceforge.net/viewvc/scst/trunk/scst/kernel/io_context-2.6.29.patch?revision=717), 
which allows SCST's I/O threads to share a single IO context.

Vlad

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