On Tue, May 24, 2016 at 12:28:09PM +0200, Jesper Dangaard Brouer wrote: > 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.
Disassemble the binaries and compare? Should be identical. Or attach gdb and look at array.producer and array.consumer. > > 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. Sounds good. > 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. Interesting. > Then I also want to know how this performs when two CPUs are involved. This has flags to pin threads to different CPUs. > As this is also a primary use-case, for you when sending packets into a > guest. > That's absolutely the primary usecase. Was designed with this in mind. > > > 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 ;-) Good idea. Will do. > [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
