Re: [Xen-devel] [PATCH] scheduler rate controller

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Sun, Dec 11, 2011 at 3:27 PM, Lv, Hui <hui.lv@xxxxxxxxx> wrote:
> Hi George,
>
> Thank you very much for your feedbacks.
> I have finished the measurement work based on the delay method. From the 
> comparable results, 1ms-delay can do as well as SRC patch to gain significant 
> performance boost without obvious drawbacks.
> 1. Basically, the "delay method" can achieve nearly the same benefits as my 
> previous SRC patch, 11% overall performance boost for SPECvirt than original 
> credit scheduler.
> 2. I have tried 1ms delay and 10ms delay, there is no big difference between 
> these two configurations. (1ms is enough to achieve a good performance)
> 3. I have compared different load level response time/latency (low, high, 
> peak), "delay method" didn't bring very much Qos increase.

Thanks Hui, those are good results.  Just one question: What's QoS
supposed to measure?  Is this a metric that SPECVirt reports?  Is
higher or lower better?

The patch looks good, but there's one last nitpick: Several of your
lines have hard tab characters in them; tabs are officially verboten
in the Xen code.  Please replace them with spaces.  After that, I
think we're ready to check it in.

One more small request: would it be possible to get some short xen
traces of SPECVirt running, at least with the 1ms-delay patch, and if
possible without it?  I'd like to have a better understanding of what
kind of scheduling workload SPECVirt creates, and how the 1ms delay
affects it.  If you have other priorities, don't worry, I'll wait
until our performance team here gets it set up.  If you do have time,
the command to use is as follows:

xentrace -D -e 0x21000 -T 30 /path/to/file.trace

This will take *just* scheduling traces for 30 seconds.  If you could
run it when the benchmark is going full throttle, that should help me
get an idea what the scheduling looks like.

Thanks,
 -George

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