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Re: [Xen-devel] credit scheduler

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] credit scheduler
From: "George Dunlap " <dunlapg@xxxxxxxxx>
Date: Tue, 29 Aug 2006 08:45:05 -0400
Cc: Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Karl Rister <kmr@xxxxxxxxxx>
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I've seen something similar... I have a cpu with two HT and two
domains (single-vcpu dom0 and an HVM domain), and I'm using the
VMEXIT/VMENTER tracing.  The most natural thing would be for each to
get its own logical cpu, but under the credit scheduler, the HVM
domain is seeing the VMENTER on a different logical cpu than it took
the VMEXIT on.  This makes the RDTSC values taken not comparable.


On 8/29/06, Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> wrote:

On 28/8/06 11:28 pm, "Karl Rister" <kmr@xxxxxxxxxx> wrote:

> This is less than ideal when considering cache warmth and the
> sharing of CPU resources when the first core of the system is always
> available in this configuration.  Does the credit scheduler have any
> awareness of cache warmth or CPU siblings when balancing?

It doesn't right now, but in your setup dom0 has its 'home core' all to
itself, so it's odd that it's bouncing around. Other cores should only steal
the domain if it is runnable but not running -- that should almost never be
the case if the domain is not contending for CPU.

 -- Keir

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