Re: [PATCH 3/3] Subject: SCHED - Use a 2-d bitmap forsearching lowest-pri CPU

From: Gregory Haskins
Date: Wed Dec 05 2007 - 08:46:41 EST


>>> On Wed, Dec 5, 2007 at 6:44 AM, in message <20071205114438.GC6143@xxxxxxx>,
Ingo Molnar <mingo@xxxxxxx> wrote:

> * Gregory Haskins <ghaskins@xxxxxxxxxx> wrote:
>
>> However, that said, Steven's testing work on the mainline port of our
>> series sums it up very nicely, so I will present that in lieu of
>> digging up my -rt numbers unless you specifically want them too. Here
>> they are:
>
> i'm well aware of Steve's benchmarking efforts, but i dont think he's
> finished with it and i'll let him present the results once he wants to
> announce them. I asked about the effects of the "2-d" patch in isolation
> and i'm not sure the numbers show that individual patch in action.

Ah, sorry if I was not clear. What I was trying to show was that you can compare "gh" to "cpupri" to see the effects of the 2-d patch in isolation (*) in Steven's tests. I believe it shows a positive impact on some tests, and a negligible impact on some tests. As long as we dont have a regression somewhere, I am happy :)

(*) Yes, "cpupri" in this test also has patches 21-22 (root-domain). However, note that Steven is not configuring cpusets, and therefore the root-domain code is effectively marginalized in this data. Its not a pure isolation, no. But the results of my tests with *true* isolation present similar characteristics, so I felt they were representative.

>
> in any case, you are preaching to the choir, i wrote the first
> rt-overload code and it's been in -rt forever so it's not like you need
> to sell me the concept ;-) But upstream quality requirements are
> different from -rt and we need to examine all aspects of scheduling, not
> just latency.

Understood and agree. I designed the subsystem with the overall system in mind, so hopefully that is reflected in the numbers and the review comments that come out of this. :)

>In any case, i'll wait for the rest of Steve's numbers.

Sounds good. Ill try to dig up my 4/8-way numbers as well for another data point.

Thanks for taking the time to review all this stuff. I know you are swamped these days.

-Greg

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