From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F661C433E0 for ; Wed, 1 Jul 2020 10:43:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA80820722 for ; Wed, 1 Jul 2020 10:43:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RALVUCmR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730047AbgGAKnw (ORCPT ); Wed, 1 Jul 2020 06:43:52 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:52085 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729939AbgGAKnv (ORCPT ); Wed, 1 Jul 2020 06:43:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593600229; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=iJDnIere4ckUlcqu2vjyvbJB29ysZfytbrXR/5K7PEs=; b=RALVUCmR9gp9sRHt4CA64SI+z5ffw291dGk7Ikx7LlRTHOmpv0Xg6c+rIwP8uAaqtw2Q9B xKxhUsRqw5qygzGw+CtObK5ZErRCfX2zvkHBRsMsev8yLq8Yoxm2Pb1M8LZ/4TWwEAUuQI GktTFF3ih0DxhtHN66GpDAdooZXs6No= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-415-lmhtQ01RNoqVVs0bor4ndA-1; Wed, 01 Jul 2020 06:43:47 -0400 X-MC-Unique: lmhtQ01RNoqVVs0bor4ndA-1 Received: by mail-qk1-f200.google.com with SMTP id k16so3525376qkh.12 for ; Wed, 01 Jul 2020 03:43:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=iJDnIere4ckUlcqu2vjyvbJB29ysZfytbrXR/5K7PEs=; b=GafPOl8sloGtlpcF55xcjUWQGemYbGH8EtsyDwEkfkpqh/zq/aEbwa7BYILBBzE+F9 y0AszYwVXGVJh7PEo5jYtW4geC4cngO0Uca6wJtDJebCzBx6QwjYmSQKAovqAfIsCNsx 85mv/iHdHucIMyLd4Eyqv6VLDoGGFd5/6Fhv9j6+O/xsFw6s6SRj+0AGFtFjUZ2LBM2f PUNM5ur9WXZ8c2toYofSG/tXLqMaZB0palAvkybBvJtzphv2JU0bk/Ndbm9qX1doI5e/ JKB6gB9PlUGowb+p33F0gXoyo1WkJSJ0UtimSQVbLi8R2Fevgs52k9Iq+ExkdxQu5/9+ MK/g== X-Gm-Message-State: AOAM532Cy0+CQDxdwtXkLK8XGsWYmlMHfEDj/rF4LgNlkJZT3b4q51El i33k77vd7xxCKethU8fYLXRTnSp29QvWQX4CuJYYoQsGD+8W01PPAyDR+TxdqHgrvkPkJi5hFvh Wus6O4sJo3xzZdnu9e+0bNtqgbrg4tQYR X-Received: by 2002:a05:620a:11b3:: with SMTP id c19mr24282750qkk.203.1593600226407; Wed, 01 Jul 2020 03:43:46 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxA+6E7kiqCtAV/8nSkNYVRZ2RneWi1RECnUnttFwOq2tXRpiCh8ne4TffX0pRmGxcg2IGuMwNPewmLwloiNcE= X-Received: by 2002:a05:620a:11b3:: with SMTP id c19mr24282729qkk.203.1593600226047; Wed, 01 Jul 2020 03:43:46 -0700 (PDT) MIME-Version: 1.0 References: <20200611113404.17810-1-mst@redhat.com> <20200611113404.17810-3-mst@redhat.com> <20200611152257.GA1798@char.us.oracle.com> <20200622114622-mutt-send-email-mst@kernel.org> <20200622122546-mutt-send-email-mst@kernel.org> In-Reply-To: From: Eugenio Perez Martin Date: Wed, 1 Jul 2020 12:43:09 +0200 Message-ID: Subject: Re: [PATCH RFC v8 02/11] vhost: use batched get_vq_desc version To: "Michael S. Tsirkin" Cc: Konrad Rzeszutek Wilk , linux-kernel@vger.kernel.org, kvm list , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Jason Wang Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jun 23, 2020 at 6:15 PM Eugenio Perez Martin wrote: > > On Mon, Jun 22, 2020 at 6:29 PM Michael S. Tsirkin 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 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 > > > > > wrote: > > > > > > > > > > > > On Thu, Jun 11, 2020 at 5:22 PM Konrad Rzeszutek Wilk > > > > > > 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 ( 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 > > > > > >