On Wed, Jul 1, 2020 at 2:40 PM Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > On 2020/7/1 下午6:43, Eugenio Perez Martin wrote: > > 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. > > > Note that for UDP_STREAM, the result is pretty trick to be analyzed. E.g > setting a sndbuf for TAP may help for the performance (reduce the drop). > Ok, will add that to the test. Thanks! > > > > >>>>>> - 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. > > > What's your setup for this. The number looks rather low. I'd expected > 1-2 Mpps at least. > Intel(R) Xeon(R) CPU E5-2650 v4 @ 2.20GHz, 2 NUMA nodes of 16G memory each, and no device assigned to the NUMA node I'm testing in. Too low for testpmd AF_PACKET driver too? > > > 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, > > > I think you meant bytes? > Yes, sorry. > > > 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), > > > What DPDK driver did you use in the test (AF_PACKET?). > Yes, both testpmd are using AF_PACKET driver. > > > 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. > > > My feeling is that if we start from simple setup, it would be more > easier as a start. E.g start without an VM. > > 1) TX: testpmd(txonly) -> virtio-user -> vhost_net -> XDP_DROP on TAP > 2) RX: pkgetn -> TAP -> vhost_net -> testpmd(rxonly) > Got it. Is there a reason to prefer pktgen over testpmd? > Thanks > > > > > > 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 >
