Re: [Xen-users] Asynchronous IO

[Andrew Warfield <andrew.warfield@xxxxxxxxx>]

Hi Priya,

I'm generally reading and writing 4KB buffers and haven't done a lot
of experimenting with other sizes.  I you want to send the source that
you are using to test throughput with, I'll take a look at how it
performs on my test box and see if I can help sort this out.

cheers,
a.

On 9/9/05, Priya, PM <pm.priya@xxxxxx> wrote:
> Hi,
> 
> Thanks for your response. Even I got 52MB/sec when I tried to do IO with
> buffer size 1 MB. But if I try to do IO with buffer size 512 Bytes, I am
> getting 0.032 MB which is 67 IOPs which is not the expected result. Have
> you tried the asynchronosu IO with different IO sizes??
> 
> I am sure I am using right version of MPT driver in Domain 0. Moreover
> the same driver performs better if I do synchronous IO in Domain 0. I am
> confused.
> 
> Thanks,
> Priya.
> 
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Andrew
> Warfield
> Sent: Thursday, September 08, 2005 11:11 PM
> To: Priya PM
> Cc: Ian Pratt; ian.pratt@xxxxxxxxxxxx; Xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] Asynchronous IO
> 
> Hi Priya,
> 
>    I regularly use libaio in domain zero as a user-space backend for
> other domains and am able to saturate a MPT fusion at about 60MB/s
> without trying too hard.  I seem to remember seeing a comment about a
> recent performance drop on the linux-aio list, possibly from 2.6.11 to
> 2.6.12, you might want to take a peek at that.  Also, are you sure that
> your XenLinux dom0 kernel has your disk driver in it, and that it isn't
> deferring to a less-efficient means of accessing the disk?
> 
> a.
> 
> On 9/9/05, Priya PM <pmpriya@xxxxxxxxx> wrote:
> > Hi,
> >
> > I tried the same operation with unstable version too. I have changed
> > the IO scheduler to atropos and tried. But no use. I always get the
> same results.
> > Has anyone checked the Asynchronous IO path using libaio?
> >
> > It would be very much helpful if you can give me some ideas to proceed
> 
> > further,
> >
> > Thanks,
> > Priya.
> >
> >
> >
> > On 9/8/05, Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx> wrote:
> > > > I have installed Xen on Linux 2.6.11.10 and i am trying to do
> > > > Asynchronous Direct IO on SAS drives. The application which does
> > > > the asynchronous direct io on SAS drive is running on Domain 0.
> > > > Actually the IOPs what i get for a 512Bytes IO size is 67, but if
> > > > i do the same operation on Linux 2.6.11.10 native kernel, i get
> > > > 267 IOPs.Can anyone tell me why this huge differnece? Am i missing
> 
> > > > something? In the current setup on Xen, if i do Synchronous IO,
> > > > then i am getting 265 IOPs which is expected. So i am wondering
> > > > why Asynchronous IO should behave this way? Is there any reason??
> > >
> > > That's odd. You might want to try the -unstable tree. I know Andy
> > > has used AIO just fine on -unstable.
> > >
> > > Ian
> > >
> >
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> >
> >
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
> 
>

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