Re: [PATCH] Make credit2 the default scheduler

From: Dario Faggioli <dfaggioli@suse.com>
To: Steven Haigh <netwiz@crc.id.au>, xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Tim Deegan <tim@xen.org>,
	george.dunlap@citrix.com, Jan Beulich <JBeulich@suse.com>,
	Ian Jackson <ian.jackson@citrix.com>
Subject: Re: [PATCH] Make credit2 the default scheduler
Date: Wed, 19 Sep 2018 11:38:05 +0200	[thread overview]
Message-ID: <73c44e93d76cf400bed6f03b4f1623448276ecf1.camel@suse.com> (raw)
In-Reply-To: <4148872.qM0LCJrPQa@wopr.lan.crc.id.au>

[-- Attachment #1.1: Type: text/plain, Size: 1861 bytes --]

On Sat, 2018-09-15 at 00:21 +1000, Steven Haigh wrote:
> On Friday, 14 September 2018 6:45:35 PM AEST Jan Beulich wrote:
> > > > > 
> > And that's despite "sched=credit2 crashes system when using
> > cpupools"? While I agree that we shouldn't delay the switch for
> > much longer, in particular with there already being a fix available
> > from you I think that one should go in before the one here.
> 
> Even though my opinion probably isn't very heavy on this matter, I've
> used 
> credit2 exclusively for a considerable time. 
>
Well, this is really interesting and useful to know. Can I ask what
your typical workload is (if any), and how are things going?

> If you're talking the issue I 
> think you're talking about, then I discovered it when doing stuff
> that most 
> people probably wouldn't bother with - evidenced that I hadn't done
> it before 
> either.
> 
Actually, we do expect the default scheduler not to crash if one
creates a cpupool.

Not that there hasn't been similar bug in Credit1, while it was the
default (check `git log' :-/). But what this all means is that we need
to do better at testing these things, e.g., finally adding cpupool and
CPU online/offline testing to OSSTest.

Anyway, the bugfix is in now. :-)

> I take peoples word on the performance +/- of a few percent here and
> there - 
> so if its easier to maintain and better code, then yeah - it makes
> sense to 
> move on with it. I certainly haven't found any normal use cases that
> would 
> lead me to object to this.
> 
Great, and thanks again for the feedback!

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Software Engineer @ SUSE https://www.suse.com/

[-- Attachment #1.2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[-- Attachment #2: Type: text/plain, Size: 157 bytes --]

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel