From: Karl Rister <kmr@us.ibm.com>
To: Xen Devel <xen-devel@lists.xensource.com>
Subject: cpu utilization monitoring
Date: Mon, 11 Sep 2006 14:44:23 -0500 [thread overview]
Message-ID: <200609111444.23398.kmr@us.ibm.com> (raw)
Currently in the vcpu_runstate_info structure we have fields that contain the
time spent when the vcpu is in one of four states. When trying to determine
the physical utilization that a vcpu is requiring of the system from libxc we
make a domctl operation call to the XEN_DOMCTL_getvcpuinfo command. When
processing this command we pull the value for the RUNSTATE_running field and
attribute it to the processor that the vcpu is currently running on.
I believe that with the new credit scheduler these values are wrong as it is
possible that the vcpu has time in RUNSTATE_running that was not actually
spent on the currently running processor. Is there a separate path through
the libraries and into Xen that retrieves this information in a more correct
manner? Given that a vcpu can migrate among several physical processors in
the time between samples it seems that a finer grained accounting mechanism
is needed to correctly report physical utilization of the hardware resources.
--
Karl Rister
IBM Linux Performance Team
kmr@us.ibm.com
next reply other threads:[~2006-09-11 19:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-11 19:44 Karl Rister [this message]
2006-09-11 19:56 ` cpu utilization monitoring Keir Fraser
2006-09-11 21:48 ` Karl Rister
2006-09-12 7:34 ` Keir Fraser
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