Re: [Xen-devel] [PATCHv1] xen-netfront: always keep the Rx ring full of requests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.10.14 at 15:33, <david.vrabel@xxxxxxxxxx> wrote:
> A full Rx ring only requires 1 MiB of memory.  This is not enough
> memory that it is useful to dynamically scale the number of Rx
> requests in the ring based on traffic rates.

The performance benefits are nice, but does the above statement
scale to hundreds of guests with perhaps multiple NICs and/or
queues?

Jan

> Keeping the ring full of Rx requests handles bursty traffic better
> than trying to converges on an optimal number of requests to keep
> filled.
> 
> On a 4 core host, an iperf -P 64 -t 60 run from dom0 to a 4 VCPU guest
> improved from 5.1 Gbit/s to 5.6 Gbit/s.  Gains with more bursty
> traffic are expected to be higher.
> 
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>



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