[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V6 net-next 0/5] xen-net{back, front}: Multiple transmit and receive queues
On Fri, 2014-03-14 at 16:10 +0000, Ian Campbell wrote: > On Mon, 2014-03-03 at 11:47 +0000, Andrew J. Bennieston wrote: > > This patch series implements multiple transmit and receive queues (i.e. > > multiple shared rings) for the xen virtual network interfaces. > > > > The series is split up as follows: > > - Patches 1 and 3 factor out the queue-specific data for netback and > > netfront respectively, and modify the rest of the code to use these > > as appropriate. > > - Patches 2 and 4 introduce new XenStore keys to negotiate and use > > multiple shared rings and event channels, and code to connect these > > as appropriate. > > - Patch 5 documents the XenStore keys required for the new feature > > in include/xen/interface/io/netif.h > > > > All other transmit and receive processing remains unchanged, i.e. there > > is a kthread per queue and a NAPI context per queue. > > > > The performance of these patches has been analysed in detail, with > > results available at: > > > > http://wiki.xenproject.org/wiki/Xen-netback_and_xen-netfront_multi-queue_performance_testing > > > > To summarise: > > * Using multiple queues allows a VM to transmit at line rate on a 10 > > Gbit/s NIC, compared with a maximum aggregate throughput of 6 Gbit/s > > with a single queue. > > * For intra-host VM--VM traffic, eight queues provide 171% of the > > throughput of a single queue; almost 12 Gbit/s instead of 6 Gbit/s. > > From the graphs it looks like 8 queues doesn't offer that much over 4 > and the bulk of the improvement comes from going to just 2 queues. > > Any idea what the bottleneck is? i.e. why does the graph flatten so > soon? It's going offbox over a 0G link isn't it, so ignore me. > > > * There is a corresponding increase in total CPU usage, i.e. this is a > > scaling out over available resources, not an efficiency improvement. > > corresponding to the number of queues or the throughput improvement? > i.e. is it 8x or 1.71x with 8 queues? > > Ian. > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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