Re: [Xen-devel] [PATCH 0/4] Implement persistent grant in xen-netfront/netback

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-11-15 at 08:38 +0000, ANNIE LI wrote:
> 
> On 2012-11-15 15:40, Pasi KÃrkkÃinen wrote:
> > Hello,
> >
> > On Thu, Nov 15, 2012 at 03:03:07PM +0800, Annie Li wrote:
> >> This patch implements persistent grants for xen-netfront/netback. This
> >> mechanism maintains page pools in netback/netfront, these page pools is 
> >> used to
> >> save grant pages which are mapped. This way improve performance which is 
> >> wasted
> >> when doing grant operations.
> >>
> >> Current netback/netfront does map/unmap grant operations frequently when
> >> transmitting/receiving packets, and grant operations costs much cpu clock. 
> >> In
> >> this patch, netfront/netback maps grant pages when needed and then saves 
> >> them
> >> into a page pool for future use. All these pages will be unmapped when
> >> removing/releasing the net device.
> >>
> > Do you have performance numbers available already? with/without persistent 
> > grants?
> I have some simple netperf/netserver test result with/without persistent 
> grants,
> 
> Following is result of with persistent grant patch,

> Guests, Sum,      Avg,     Min,     Max
>   1,  15106.4,  15106.4, 15106.36, 15106.36
>   2,  13052.7,  6526.34,  6261.81,  6790.86
>   3,  12675.1,  6337.53,  6220.24,  6454.83
>   4,  13194,  6596.98,  6274.70,  6919.25

Are these pairs of guests or individual ones?

I think the really interesting cases are when you get up to larger
numbers of guests, aren't they? ISTR that for blkio things got most
interesting WRT persistent grants at the dozens of guests stage. Do you
have any numbers for those?

Have you run any tests other than netperf?

Do you have numbers for a a persistent capable backend with a
non-persistent frontend and vice versa?


> 
> 
> Following are result of without persistent patch
> 
> Guests, Sum,     Avg,    Min,        Max
>   1,  10864.1,  10864.1, 10864.10, 10864.10
>   2,  10898.5,  5449.24,  4862.08,  6036.40
>   3,  10734.5,  5367.26,  5261.43,  5473.08
>   4,  10924,    5461.99,  5314.84,  5609.14



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