On Wed, Jul 1, 2020 at 4:10 PM Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > On 2020/7/1 下午9:04, Eugenio Perez Martin wrote: > > 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! > > > Actually, it's better to skip the UDP_STREAM test since: > > - My understanding is very few application is using raw UDP stream > - It's hard to analyze (usually you need to count the drop ratio etc) > > > > > >>>>>>>> - 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? > > > I don't test AF_PACKET, I guess it should use the V3 which mmap based > zerocopy interface. > > And it might worth to check the cpu utilization of vhost thread. It's > required to stress it as 100% otherwise there could be a bottleneck > somewhere. > > > > > >>> 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. > > > I see, using AF_PACKET means extra layers of issues need to be analyzed > which is probably not good. > > > > > >>> 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? > > > I think the reason is using testpmd you must use a userspace kernel > interface (AF_PACKET), and it could not be as fast as pktgen since: > > - it talks directly to xmit of TAP > - skb can be cloned > Hi! Here it is the result of the tests. Details on [1]. Tx: === For tx packets it seems that the batching patch makes things a little bit worse, but the buf_api outperforms baseline by a 7%: * We start with a baseline of 4208772.571 pps and 269361444.6 bytes/s [2]. * When we add the batching, I see a small performance decrease: 4133292.308 and 264530707.7 bytes/s. * However, the buf api it outperform the baseline: 4551319.631pps, 291205178.1 bytes/s I don't have numbers on the receiver side since it is just a XDP_DROP. I think it would be interesting to see them. Rx: === Regarding Rx, the reverse is observed: a small performance increase is observed with batching (~2%), but buf_api makes tests perform equally to baseline. pktgen was called using pktgen_sample01_simple.sh, with the environment: DEV="$tap_name" F_THREAD=1 DST_MAC=$MAC_ADDR COUNT=$((2500000*25)) SKB_CLONE=$((2**31)) And testpmd is the same as Tx but with forward-mode=rxonly. Pktgen reports: Baseline: 1853025pps 622Mb/sec (622616400bps) errors: 7915231 Batch: 1891404pps 635Mb/sec (635511744bps) errors: 4926093 Buf_api: 1844008pps 619Mb/sec (619586688bps) errors: 47766692 Testpmd reports: Baseline: 1854448pps, 860464156 bps. [3] Batch: 1892844.25pps, 878280070bps. Buf_api: 1846139.75pps, 856609120bps. Any thoughts? Thanks! [1] Testpmd options: -l 1,3 --vdev=virtio_user0,mac=01:02:03:04:05:06,path=/dev/vhost-net,queue_size=1024 -- --auto-start --stats-period 5 --tx-offloads="$TX_OFFLOADS" --rx-offloads="$RX_OFFLOADS" --txd=4096 --rxd=4096 --burst=512 --forward-mode=txonly Where offloads were obtained manually running with --[tr]x-offloads=0x8fff and examining testpmd response: declare -r RX_OFFLOADS=0x81d declare -r TX_OFFLOADS=0x802d All of the tests results are an average of at least 3 samples of testpmd, discarding the obvious deviations at start/end (like warming up or waiting for pktgen to start). The result of pktgen is directly c&p from its output. The numbers do not change very much from one stats printing to another of testpmd. [2] Obtained subtracting each accumulated tx-packets from one stats print to the previous one. If we attend testpmd output about Tx-pps, it counts a little bit less performance, but it follows the same pattern: Testpmd pps/bps stats: Baseline: 3510826.25 pps, 1797887912bps = 224735989bytes/sec Batch: 3448515.571pps, 1765640226bps = 220705028.3bytes/sec Buf api: 3794115.333pps, 1942587286bps = 242823410.8bytes/sec [3] This is obtained using the rx-pps/rx-bps report of testpmd. Seems strange to me that the relation between pps/bps is ~336 this time, and between accumulated pkts/accumulated bytes is ~58. Also, the relation between them is not even close to 8. However, testpmd shows a lot of absolute packets received. If we see the received packets in a period subtracting from the previous one, testpmd tells that receive more pps than pktgen tx-pps: Baseline: ~2222668.667pps 128914784.3bps. Batch: 2269260.933pps, 131617134.9bps Buf_api: 2213226.467pps, 128367135.9bp
