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

[Xen-devel] Measuring intra-CPU stime skew

To: "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>
Subject: [Xen-devel] Measuring intra-CPU stime skew
From: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Date: Tue, 22 Jul 2008 07:46:27 -0600
Cc: Dave Winchell <dwinchell@xxxxxxxxxxxxxxx>
Delivery-date: Tue, 22 Jul 2008 06:52:01 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
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>
Organization: Oracle Corporation
Reply-to: "dan.magenheimer@xxxxxxxxxx" <dan.magenheimer@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcjsAVQscccFDTJnS0ii3ee6zym5SA==
With the attached patch, I am trying to measure maximum
intra-CPU stime skew.  This is not (necessarily) intended
to be applied, but I'd be very interested in review to
see if I am measuring it accurately or if there might
be other more accurate methods than these three.

I'd also be interested in measurements from other machines
and configurations.  (Output obtained with "xm debug-key t"
which can be iterated in a shell loop to collect samples
for one of the collection methods... they others are
collected automatically.)

If it is accurate, skew is worse than I had previously
thought.  Not horribly worse, but I am seeing 30-40us
skew (on hpet) instead of the 11us I was seeing before.

Thanks,
Dan


===================================
Thanks... for the memory
I really could use more / My throughput's on the floor
The balloon is flat / My swap disk's fat / I've OOM's in store
Overcommitted so much
(with apologies to the late great Bob Hope)

Attachment: recordskew.patch
Description: Binary data

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
<Prev in Thread] Current Thread [Next in Thread>
  • [Xen-devel] Measuring intra-CPU stime skew, Dan Magenheimer <=