WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] [PATCH] Quick path for PIO instructions which cut more t

To: "Xiang, Kai" <kai.xiang@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Quick path for PIO instructions which cut more than half of the expense
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 22 Dec 2008 10:43:32 +0000
Cc:
Delivery-date: Mon, 22 Dec 2008 02:43:33 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C85CEDA13AB1CF4D9D597824A86D2B9001C3D4771E@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AclkHlHyULdzldIRRfyHPzvdmtg6NAAA9Aeu
Thread-topic: [Xen-devel] [PATCH] Quick path for PIO instructions which cut more than half of the expense
User-agent: Microsoft-Entourage/12.14.0.081024
On 22/12/2008 10:16, "Xiang, Kai" <kai.xiang@xxxxxxxxx> wrote:

> 3) The influence for more realistic workloads:
> We tested on Windows 2003 Server Guest, while using IOmeter to run a Disk
> bound test, the IO pattern is "Default" which use 67% random read and 33%
> random write with 2K request size.
> To reduce the influence of file cache, I run 3 times (1 minutes each) from the
> start of the computer (both xen and the guest)
> 
> Compare before and after
>          IO per second (3 runs)    |  average response time (3 runs)
> ----------------------------------------------------------------
> Before: 100.004; 109.447; 110.801  |  9.988;  9.133;  9.022
> After:  101.951; 110.893; 114.179  |  9.806;  9.016;  8.756
> ------------------------------------------------------------------
> 
> So we are having a 1%~3% percent IO performance gain while reduce the average
> response time by 2%~3% at the same time.
> Considering this is just an ordinary SATA disk and an IO bound workload, we
> are expecting more with faster Disks and more cached IO.

The difference is in the noise, almost. Not, I think, sufficient for me ever
to want to see the VMX PIO code back in Xen ever again. Those who actually
care about performance would run PV drivers anyway, and see much greater
speedups.

 -- Keir



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

<Prev in Thread] Current Thread [Next in Thread>