From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> Date: Sat, 2 Aug 2014 10:42:02 -0700 > Intel did some benchmarking on our network throughput when Linux on Hyper-V > is as used as a gateway. This fix gave us almost a 1 Gbps additional throughput > on about 5Gbps base throughput we hadi, prior to increasing the sendbuf size. > The sendbuf mechanism is a copy based transport that we have which is clearly > more optimal than the copy-free page flipping mechanism (for small packets). > In the forwarding scenario, we deal only with MTU sized packets, > and increasing the size of the senbuf area gave us the additional performance. > For what it is worth, Windows guests on Hyper-V, I am told use similar sendbuf > size as well. > > The exact value of sendbuf I think is less important than the fact that it needs > to be larger than what Linux can allocate as physically contiguous memory. > Thus the change over to allocating via vmalloc(). > > We currently allocate 16MB receive buffer and we use vmalloc there for allocation. > Also the low level channel code has already been modified to deal with physically > dis-contiguous memory in the ringbuffer setup. > > Based on experimentation Intel did, they say there was some improvement in throughput > as the sendbuf size was increased up to 16MB and there was no effect on throughput > beyond 16MB. Thus I have chosen 16MB here. > > Increasing the sendbuf value makes a material difference in small packet handling > > In this version of the patch, based on David's feedback, I have added > additional details in the commit log. > > > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> APplied. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
