On Mon, 23 May 2016 23:52:47 +0300 "Michael S. Tsirkin" <m...@redhat.com> wrote:
> On Mon, May 23, 2016 at 03:09:18PM +0200, Jesper Dangaard Brouer wrote: > > On Mon, 23 May 2016 13:43:46 +0300 > > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > > > Add ringtest based unit test for skb array. > > > > > > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> > > > --- > > > tools/virtio/ringtest/skb_array.c | 167 > > > ++++++++++++++++++++++++++++++++++++++ > > > tools/virtio/ringtest/Makefile | 4 +- > > > > Patch didn't apply cleanly to Makefile, as you also seems to have > > "virtio_ring_inorder", I manually applied it. > > > > I chdir to tools/virtio/ringtest/ and I could compile "skb_array", > > BUT how do I use it??? (the README is not helpful) > > > > What is the "output", are there any performance measurement results? > > First, if it completes successfully this means it completed > a ton of cycles without errors. It caches any missing barriers > which aren't nops on your system. I applied these patches on net-next (at commit 07b75260e) and the skb_array test program never terminates. Strangely if I use your git tree[1] (on branch vhost) the program does terminate... I didn't spot the difference. > Second - use perf. I do like perf, but it does not answer my questions about the performance of this queue. I will code something up in my own framework[2] to answer my own performance questions. Like what is be minimum overhead (in cycles) achievable with this type of queue, in the most optimal situation (e.g. same CPU enq+deq cache hot) for fastpath usage. Then I also want to know how this performs when two CPUs are involved. As this is also a primary use-case, for you when sending packets into a guest. > E.g. simple perf stat will measure how long does it take to execute. > there's a script that runs it on different CPUs, > so I normally do: > > sh run-on-all.sh perf stat -r 5 ./skb_array I recommend documenting this in the README file in the same dir ;-) [1] https://git.kernel.org/cgit/linux/kernel/git/mst/vhost.git/log/?h=vhost [2] https://github.com/netoptimizer/prototype-kernel -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer
