Re: [PATCH 1/3] Make credit2 the default scheduler

From: Dario Faggioli <dfaggioli@suse.com>
To: George Dunlap <george.dunlap@citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>, Tim Deegan <tim@xen.org>,
	Jan Beulich <jbeulich@suse.com>,
	Ian Jackson <ian.jackson@citrix.com>
Subject: Re: [PATCH 1/3] Make credit2 the default scheduler
Date: Mon, 05 Feb 2018 17:53:21 +0100	[thread overview]
Message-ID: <1517849601.8082.10.camel@suse.com> (raw)
In-Reply-To: <d9a9e4c9-1a78-ac26-0bda-cea8e842e05d@citrix.com>

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On Mon, 2018-02-05 at 13:01 +0000, George Dunlap wrote:
> On 02/05/2018 11:45 AM, Andrew Cooper wrote:
> > 
> Here is a summary of data from an intern e-mail Dario sent about 6
> months ago:
> 
> * DVDbench: On underloaded systems, credit2 outperformed credit1 by
> about 4%.  On overloaded systems, credit2 underperformed by about 3%.
> 
> * On a range of tests (unixbench, lmbench, &c), credit and credit2
> perform within 5% of each other (up and down).
> 
> * Credit2 fairly consistently beats credit for TCP-style workloads.
> 
> * Credit2 is sometimes equal to, sometimes 5-15% worse than, credit
> for
> synthetic CPU workloads (e.g., Dhrystone).
> 
> * On LoginVSI, credit2 fairly consistently outperforms credit by
> about 10%.
> 
Thanks George for summing this up!

> Credit2, like credit, has a number of workloads / setups for which
> performance could be improved.  Personally I think networking and
> partially-loaded systems is going to be more representative of what
> Xen
> is actually used for; so I think credit2 is on the whole the better
> scheduler to use by default.  
>
I'm sure this will sound no surprise for anyone, but allow me to say it
anyway: I agree with George. :-D

> And in any case, making those improvements
> on credit2 will be easier than on credit.
> 
And, if possible, I agree with George on this even more!

One thing I think we should consider, though, is that we've often said
we would switch at the very beginning of a dev cycle, to get as much as
osstest and day-by-day testing from developer as possible.

Considering we're releasing in June, but freezing in March, do we think
 it is still early enough?

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/

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