Messages in this thread |  | | | Subject | Re: [PATCH v2 3/6] KVM-GST: KVM Steal time accounting | | From | Glauber Costa <> | | Date | Tue, 01 Feb 2011 13:57:04 -0200 |
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On Sun, 2011-01-30 at 16:04 +0200, Avi Kivity wrote: > On 01/28/2011 09:52 PM, Glauber Costa wrote: > > This patch accounts steal time time in kernel/sched. > > I kept it from last proposal, because I still see advantages > > in it: Doing it here will give us easier access from scheduler > > variables such as the cpu rq. The next patch shows an example of > > usage for it. > > > > Since functions like account_idle_time() can be called from > > multiple places, not only account_process_tick(), steal time > > grabbing is repeated in each account function separatedely. > > > > I accept that steal time is worthwhile, but do you have some way to > demonstrate that the implementation actually works and is beneficial? > > Perhaps run two cpu-bound compute processes on one vcpu, overcommit that > vcpu, and see what happens to the processing rate with and without steal > time accounting. I'd expect a fairer response with steal time accounting.
Avi,
There are two things here: One of them, which is solely the accounting of steal time, (patches 1 to 4) has absolutely nothing to do with what you said. Its sole purpose is to provide the user with information about "why is my process slow if I am using 100 % of my cpu?")
The last patch is the only one that actually tries to rebalance cpus according to steal time information. For that, I do have some experiments I did here to see if it is working, will try to provide more precise data in the next submission.
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