Re: [RFC PATCH v3 00/16] Core scheduling v3

[Dario Faggioli]

Hello everyone,

This is Dario, from SUSE. I'm also interesting in core-scheduling, and
using it in virtualization use cases.

Just for context, I'm working in virt since a few years, mostly on Xen,
but I've done Linux stuff before, and I am getting back at it.

For now, I've been looking at the core-scheduling code, and run some
benchmarks myself.

On Fri, 2019-08-02 at 11:37 -0400, Julien Desfossez wrote:
> We tested both Aaron's and Tim's patches and here are our results.
> 
> Test setup:
> - 2 1-thread sysbench, one running the cpu benchmark, the other one
> the
>   mem benchmark
> - both started at the same time
> - both are pinned on the same core (2 hardware threads)
> - 10 30-seconds runs
> - test script: https://paste.debian.net/plainh/834cf45c
> - only showing the CPU events/sec (higher is better)
> - tested 4 tag configurations:
>   - no tag
>   - sysbench mem untagged, sysbench cpu tagged
>   - sysbench mem tagged, sysbench cpu untagged
>   - both tagged with a different tag
> - "Alone" is the sysbench CPU running alone on the core, no tag
> - "nosmt" is both sysbench pinned on the same hardware thread, no tag
> - "Tim's full patchset + sched" is an experiment with Tim's patchset
>   combined with Aaron's "hack patch" to get rid of the remaining deep
>   idle cases
> - In all test cases, both tasks can run simultaneously (which was not
>   the case without those patches), but the standard deviation is a
>   pretty good indicator of the fairness/consistency.
> 
This, and of course the numbers below too, is very interesting.

So, here comes my question: I've done a benchmarking campaign (yes,
I'll post numbers soon) using this branch:

https://github.com/digitalocean/linux-coresched.git  vpillai/coresched-v3-v5.1.5-test
https://github.com/digitalocean/linux-coresched/tree/vpillai/coresched-v3-v5.1.5-test

Last commit:
7feb1007f274 "Fix stalling of untagged processes competing with tagged
processes"

Since I see that, in this thread, there are various patches being
proposed and discussed... should I rerun my benchmarks with them
applied? If yes, which ones? And is there, by any chance, one (or maybe
more than one) updated git branch(es)?

Thanks in advance and Regards
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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