Re: [Xen-devel] [PATCH 0/3 V2] xen-netback: switch to NAPI + kthread 1:1 model

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jun 11, 2013 at 11:06:43AM +0100, David Vrabel wrote:
> On 27/05/13 12:29, Wei Liu wrote:
> > * This is a xen-devel only post, since we have not reached concesus on
> >   what to add / remove in this new model. This series tries to be
> >   conservative about adding in new feature compared to V1.
> > 
> > This series implements NAPI + kthread 1:1 model for Xen netback.
> > 
> > This model
> >  - provides better scheduling fairness among vifs
> >  - is prerequisite for implementing multiqueue for Xen network driver
> > 
> > The first two patches are ground work for the third patch. First one
> > simplifies code in netback, second one can reduce memory footprint if we
> > switch to 1:1 model.
> > 
> > The third patch has the real meat:
> >  - make use of NAPI to mitigate interrupt 
> >  - kthreads are not bound to CPUs any more, so that we can take
> >    advantage of backend scheduler and trust it to do the right thing
> > 
> > Change since V1:
> >  - No page pool in this version. Instead page tracking facility is
> >    removed.
> 
> Andrew Bennieston has done some performance measurements with (I think)
> the V1 series and it shows a significant decrease in performance of
> from-guest traffic even with only two VIFs.
> 
> Andrew will be able to comment more on this.
> 
> Andrew, can you also make available your results for others to review?
> 

In my third series there is also simple performance figures attached.
Andrew could you please have a look at that as well?

If you have time, could you try my third series? In the third series,
the only possible performance impact is the new model, which should
narrow the problem down.


Wei.

> David

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