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[Xen-devel] Re: [Xen-users] About profiling xen

To: Fasiha Ashraf <feehapk@xxxxxxxxxxx>
Subject: [Xen-devel] Re: [Xen-users] About profiling xen
From: Marco Tizzoni <marco.tizzoni@xxxxxxxxx>
Date: Wed, 30 Sep 2009 08:33:19 +0200
Cc: "Fajar A." <fajar@xxxxxxxxx>, xen <xen-devel@xxxxxxxxxxxxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
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I experienced the same problem with netperf and with hping also. In general every tool that sends packet at fixed rates seems to suffer this problem. If you use the flood option ( sends packets as fast as possible - for example 'ping -f' or 'hping3 -f') instead of a fixed rate the rate become much higher. What I discovered is this issue should be related to Xen's signal handling/delivery.
Netperf use setitimer() to send packets at fixed rate. In my experience on dom0/U, with no load, Xen cannot go over 250 signals per second. Because netperf use signal wakeup the function that send packets I think your problem can be related to this issue. If you want to be sure, count the average number of packet per seconds. It should be about 250 packets/s (not more).
For more info you can see this:http://lists.xensource.com/archives/html/xen-devel/2009-09/msg01159.html


On Wed, Sep 30, 2009 at 8:07 AM, Fasiha Ashraf <feehapk@xxxxxxxxxxx> wrote:
Hi there,
I am getting very low throughput (around 0.29Mbps) while running netperf benchmark for guest to guest communication on a single physical host. To analyse where the time is spent in hypervisor I wanna use profiling. Please help me choosing good profiler according to my requirments. Should it be better in my case, Xentrace, gprof, xenoprof  or Oprofile. Is it possible to use some vtune version on FC11?

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