On Tue, Jun 23, 2020 at 6:15 PM Eugenio Perez Martin <eperezma@xxxxxxxxxx> wrote: > > On Mon, Jun 22, 2020 at 6:29 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > On Mon, Jun 22, 2020 at 06:11:21PM +0200, Eugenio Perez Martin wrote: > > > On Mon, Jun 22, 2020 at 5:55 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > > > > > On Fri, Jun 19, 2020 at 08:07:57PM +0200, Eugenio Perez Martin wrote: > > > > > On Mon, Jun 15, 2020 at 2:28 PM Eugenio Perez Martin > > > > > <eperezma@xxxxxxxxxx> wrote: > > > > > > > > > > > > On Thu, Jun 11, 2020 at 5:22 PM Konrad Rzeszutek Wilk > > > > > > <konrad.wilk@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > On Thu, Jun 11, 2020 at 07:34:19AM -0400, Michael S. Tsirkin wrote: > > > > > > > > As testing shows no performance change, switch to that now. > > > > > > > > > > > > > > What kind of testing? 100GiB? Low latency? > > > > > > > > > > > > > > > > > > > Hi Konrad. > > > > > > > > > > > > I tested this version of the patch: > > > > > > https://lkml.org/lkml/2019/10/13/42 > > > > > > > > > > > > It was tested for throughput with DPDK's testpmd (as described in > > > > > > http://doc.dpdk.org/guides/howto/virtio_user_as_exceptional_path.html) > > > > > > and kernel pktgen. No latency tests were performed by me. Maybe it is > > > > > > interesting to perform a latency test or just a different set of tests > > > > > > over a recent version. > > > > > > > > > > > > Thanks! > > > > > > > > > > I have repeated the tests with v9, and results are a little bit different: > > > > > * If I test opening it with testpmd, I see no change between versions > > > > > > > > > > > > OK that is testpmd on guest, right? And vhost-net on the host? > > > > > > > > > > Hi Michael. > > > > > > No, sorry, as described in > > > http://doc.dpdk.org/guides/howto/virtio_user_as_exceptional_path.html. > > > But I could add to test it in the guest too. > > > > > > These kinds of raw packets "bursts" do not show performance > > > differences, but I could test deeper if you think it would be worth > > > it. > > > > Oh ok, so this is without guest, with virtio-user. > > It might be worth checking dpdk within guest too just > > as another data point. > > > > Ok, I will do it! > > > > > > * If I forward packets between two vhost-net interfaces in the guest > > > > > using a linux bridge in the host: > > > > > > > > And here I guess you mean virtio-net in the guest kernel? > > > > > > Yes, sorry: Two virtio-net interfaces connected with a linux bridge in > > > the host. More precisely: > > > * Adding one of the interfaces to another namespace, assigning it an > > > IP, and starting netserver there. > > > * Assign another IP in the range manually to the other virtual net > > > interface, and start the desired test there. > > > > > > If you think it would be better to perform then differently please let me know. > > > > > > Not sure why you bother with namespaces since you said you are > > using L2 bridging. I guess it's unimportant. > > > > Sorry, I think I should have provided more context about that. > > The only reason to use namespaces is to force the traffic of these > netperf tests to go through the external bridge. To test netperf > different possibilities than the testpmd (or pktgen or others "blast > of frames unconditionally" tests). > > This way, I make sure that is the same version of everything in the > guest, and is a little bit easier to manage cpu affinity, start and > stop testing... > > I could use a different VM for sending and receiving, but I find this > way a faster one and it should not introduce a lot of noise. I can > test with two VM if you think that this use of network namespace > introduces too much noise. > > Thanks! > > > > > > > > > > - netperf UDP_STREAM shows a performance increase of 1.8, almost > > > > > doubling performance. This gets lower as frame size increase. Regarding UDP_STREAM: * with event_idx=on: The performance difference is reduced a lot if applied affinity properly (manually assigning CPU on host/guest and setting IRQs on guest), making them perform equally with and without the patch again. Maybe the batching makes the scheduler perform better. > > > > > - rests of the test goes noticeably worse: UDP_RR goes from ~6347 > > > > > transactions/sec to 5830 * Regarding UDP_RR, TCP_STREAM, and TCP_RR, proper CPU pinning makes them perform similarly again, only a very small performance drop observed. It could be just noise. ** All of them perform better than vanilla if event_idx=off, not sure why. I can try to repeat them if you suspect that can be a test failure. * With testpmd and event_idx=off, if I send from the VM to host, I see a performance increment especially in small packets. The buf api also increases performance compared with only batching: Sending the minimum packet size in testpmd makes pps go from 356kpps to 473 kpps. Sending 1024 length UDP-PDU makes it go from 570kpps to 64 kpps. Something strange I observe in these tests: I get more pps the bigger the transmitted buffer size is. Not sure why. ** Sending from the host to the VM does not make a big change with the patches in small packets scenario (minimum, 64 bytes, about 645 without the patch, ~625 with batch and batch+buf api). If the packets are bigger, I can see a performance increase: with 256 bits, it goes from 590kpps to about 600kpps, and in case of 1500 bytes payload it gets from 348kpps to 528kpps, so it is clearly an improvement. * with testpmd and event_idx=on, batching+buf api perform similarly in both directions. All of testpmd tests were performed with no linux bridge, just a host's tap interface (<interface type='ethernet'> in xml), with a testpmd txonly and another in rxonly forward mode, and using the receiving side packets/bytes data. Guest's rps, xps and interrupts, and host's vhost threads affinity were also tuned in each test to schedule both testpmd and vhost in different processors. I will send the v10 RFC with the small changes requested by Stefan and Jason. Thanks! > > > > > > > > OK so it seems plausible that we still have a bug where an interrupt > > > > is delayed. That is the main difference between pmd and virtio. > > > > Let's try disabling event index, and see what happens - that's > > > > the trickiest part of interrupts. > > > > > > > > > > Got it, will get back with the results. > > > > > > Thank you very much! > > > > > > > > > > > > > > > > - TCP_STREAM goes from ~10.7 gbps to ~7Gbps > > > > > - TCP_RR from 6223.64 transactions/sec to 5739.44 > > > > > >
