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Re: [Xen-users] Credit Scheduler

To: Dustin.Henning@xxxxxxxxxxx
Subject: Re: [Xen-users] Credit Scheduler
From: Florian Schmaus <flo4lists@xxxxxxxxxx>
Date: Mon, 01 Dec 2008 16:37:49 +0100
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Both domUs have 2 VCPUs:

Name ID VCPUs CPU State Time(s) CPU Affinity
Domain-0                        0     0             0   r--    1738.8 0
Domain-0                         0     1             1   -b-     532.0 1
web 6 0 1 r-- 422829.0 any cpu web 6 1 0 --- 422758.0 any cpu boinc 2 0 0 -b- 5096.9 any cpu boinc 2 1 1 -b- 928.2 any cpu


Dustin Henning wrote:
        Just a wild guess, but do both domUs have single VCPUs with a
different CPU assigned?  It seems reasonable to assume that the domUs would
have to be using the same CPU(s) in order for the priority to come into
play.  Assuming I am correct there, they should have the same CPU assigned
if they are using one VCPU; if they are using two VCPUs then they should
each be using both CPUs anyway, and in either of the aforementioned
scenarios, the priority should come in to play.

-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Florian Schmaus
Sent: Monday, December 01, 2008 10:24
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Credit Scheduler

I have a CentOS 5.2 Dual-Core Host with two domU's. One domU is for apache and postfix, the other one is just for BOINC. I thought that I can configure the XEN credit scheduler in such a manner, that the BOINC domU only gets CPU resources if the other one, the "important" one, has nothing else to do. After a "xm sched-credit -d boinc -w 1" and "xm sched-credit -d web -w 200" I run a CPU benchmark on the "web" domU. I expected that the "web" domU would get 199% CPU share and the boinc domU just 1%, because the "web" domU hast 200 times more weight than the BOINC domU. But the credit scheduler gave both domU's about 100% CPU share.
What am I missing here?

xm dmesg shows "(XEN) Using scheduler: SMP Credit Scheduler (credit)"
and "xm sched_credit -d web" also confirms that the weight is set correctly.


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