Re: [Xen-devel] [PATCH 1/2] cpu steal time accounting

[Rik van Riel <riel@xxxxxxxxxx>]

On Tue, 21 Feb 2006, Keir Fraser wrote:

> Looking at the other patch, I think I'm missing higher level context 
> regarding what this patch is about. I grepped around for 
> account_steal_time() -- looks like it's currently used by s390, but as 
> part of a rather bigger patch that also calls 
> account_user_time/account_system_time.

Basically steal time is the amount of time when:
1) we had a runnable task, but
2) it was not running, because our vcpu was scheduled
   away by the hypervisor

Thus, steal time measures how much a particular workload
inside a virtual machine is impacted by contention on the
cpu between different virtual machines.

It also makes sure that time the vcpu itself was not running
is not erroneously accounted to the currently running process,
which matters when a user is trying to determine how much CPU
time a particular task needs.

-- 
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