Re: [Xen-devel] [for-4.8 PATCH] xen: credit2: make runqueues be per-socket by default.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Nov 29, 2016 at 04:51:04AM -0700, Jan Beulich wrote:
> >>> On 29.11.16 at 12:42, <wei.liu2@xxxxxxxxxx> wrote:
> > On Tue, Nov 29, 2016 at 12:33:24PM +0100, Dario Faggioli wrote:
> >> On Tue, 2016-11-29 at 11:14 +0000, Wei Liu wrote:
> >> > On Tue, Nov 29, 2016 at 11:57:03AM +0100, Dario Faggioli wrote:
> >> > Strictly speaking, this is not necessary for 4.8 because even though
> >> > the
> >> > default configuration is not optimal, there is a simple way to change
> >> > it.
> >> > 
> >> Absolutely true.
> >> 
> >> > On the other hand, because credit2 is declared supported in this
> >> > release, it is better to have a sensible default setting for credit2.
> >> > 
> >> Exactly.
> >> 
> >> > The risk is that changing the default value would cause osstest to
> >> > discover bugs in the scheduler logic, hence blocking the release. But
> >> > overall I think the chance is low, but Dario can you please state to
> >> > what extend did you test this patch?
> >> > 
> >> I've tried to state that in the cover letter:
> >> https://lists.xen.org/archives/html/xen-devel/2016-11/msg02616.html 
> >> 
> > 
> > Ah, I thought that was a dupe because it had the same subject line as
> > the patch, so I skipped it.
> 
> Same here, albeit I had noticed I shouldn't have got 2 copies, so
> I did look into the other one.
> 
> >> In some more details, it is _months_ that I and Anshul run benchmarks
> >> with Credit2 running in this configuration.
> >> 
> >> It's months that, all the time that I boot my test box, either to do
> >> Credit2 related development and testing, or completely unrelated things
> >> (e.g., recently, when testing the new Fedora 25 as HVM and PV guest), I
> >> use Credit2 in this configuration.
> >> 
> >> George has done some runs of his schedbench suite with this
> >> configuration (to compare Credit1 vs Credit2 per-core vs Credit2 per-
> >> socket).
> >> 
> >> So, if you ask me "how much is this tested", my answer would be "really
> >> really really a lot". :-)
> >> 
> > 
> > OK. This is rather convincing to me. I will wait a bit for other people
> > express their opinion.
> 
> FWIW, I'm in favor of putting it in with the background provided.
> 

Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Feel free to commit it with your other patches.

> Jan
> 

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