[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH net-next v2 0/9] xen-netback: TX grant mapping with SKBTX_DEV_ZEROCOPY instead of copy

On 16/12/13 06:32, annie li wrote:

On 2013/12/13 7:48, Zoltan Kiss wrote:
A long known problem of the upstream netback implementation that on
the TX
path (from guest to Dom0) it copies the whole packet from guest memory
Dom0. That simply became a bottleneck with 10Gb NICs, and generally
it's a
huge perfomance penalty. The classic kernel version of netback used grant
mapping, and to get notified when the page can be unmapped, it used page
destructors. Unfortunately that destructor is not an upstreamable
Ian Campbell's skb fragment destructor patch series [1] tried to solve
problem, however it seems to be very invasive on the network stack's
and therefore haven't progressed very well.
This patch series use SKBTX_DEV_ZEROCOPY flags to tell the stack it
needs to
know when the skb is freed up. That is the way KVM solved the same
and based on my initial tests it can do the same for us. Avoiding the
copy boosted up TX throughput from 6.8 Gbps to 7.9 (I used a slower
Interlagos box, both Dom0 and guest on upstream kernel, on the same
NUMA node,
running iperf 2.0.5, and the remote end was a bare metal box on the
same 10Gb
Sounds good.
Is the TX throughput gotten between one vm and one bare metal box? or
between multiple vms and bare metal? Do you have any test results with
One VM and a bare metal box. I've used only iperf.



Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.