Re: [Xen-devel] Poor network performance between DomU with multiqueue support

["Zhangleiqiang (Trump)" <zhangleiqiang@xxxxxxxxxx>]

> On Mon, Dec 08, 2014 at 01:08:18PM +0000, Zhangleiqiang (Trump) wrote:
> > > On Mon, Dec 08, 2014 at 06:44:26AM +0000, Zhangleiqiang (Trump) wrote:
> > > > > On Fri, Dec 05, 2014 at 01:17:16AM +0000, Zhangleiqiang (Trump)
> wrote:
> > > > > [...]
> > By the way, after rethinking the testing results for multi-queue pv
> > (kernel 3.17.4+XEN 4.4) implementation, I find that when using four
> > queues for netback/netfront, there will be about 3 netback process
> > running with high CPU usage on receive Dom0 (about 85% usage per
> > process running on one CPU core), and the aggregate throughout is only
> > about 5Gbps. I doubt that there may be some bug or pitfall in current
> > multi-queue implementation, because for 5Gbps throughout, occurring
> > about all of 3 CPU core for packet receiving is somehow abnormal.
> >
> 
> 3.17.4 doesn't contain David Vrabel's fixes.
> 
> Look for
>   bc96f648df1bbc2729abbb84513cf4f64273a1f1
>   f48da8b14d04ca87ffcffe68829afd45f926ec6a
>   ecf08d2dbb96d5a4b4bcc53a39e8d29cc8fef02e
> in David Miller's net tree.

I have tried to testing with 3.18-rc5 which including these patches, however, 
it seems that the problem mentioned is not improved. There are still 3 netback 
receive processes each of which uses about 85% of CPU core.

> BTW there are some improvement planned for 4.6: "[Xen-devel] [PATCH v3 0/2]
> gnttab: Improve scaleability". This is orthogonal to the problem you're 
> trying to
> solve but it should help improve performance in general.
> 
> 
> Wei.

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