From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id B008CA057C for ; Fri, 27 Mar 2020 19:24:41 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 99EA21C239; Fri, 27 Mar 2020 19:24:41 +0100 (CET) Received: from inbox.dpdk.org (xvm-172-178.dc0.ghst.net [95.142.172.178]) by dpdk.org (Postfix) with ESMTP id 3F5CF1C21A for ; Fri, 27 Mar 2020 19:24:40 +0100 (CET) Received: by inbox.dpdk.org (Postfix, from userid 33) id 19BF6A058E; Fri, 27 Mar 2020 19:24:40 +0100 (CET) From: bugzilla@dpdk.org To: ci@dpdk.org Date: Fri, 27 Mar 2020 18:24:39 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: lab X-Bugzilla-Component: job scripts X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: major X-Bugzilla-Who: lylavoie@iol.unh.edu X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: Normal X-Bugzilla-Assigned-To: ci@dpdk.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter cc target_milestone Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://bugs.dpdk.org/ Auto-Submitted: auto-generated X-Auto-Response-Suppress: All MIME-Version: 1.0 Subject: [dpdk-ci] [Bug 429] New Perf Test Case: Test above / below maximum throughput of NIC / system X-BeenThere: ci@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK CI discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: ci-bounces@dpdk.org Sender: "ci" https://bugs.dpdk.org/show_bug.cgi?id=3D429 Bug ID: 429 Summary: New Perf Test Case: Test above / below maximum throughput of NIC / system Product: lab Version: unspecified Hardware: All OS: All Status: UNCONFIRMED Severity: major Priority: Normal Component: job scripts Assignee: ci@dpdk.org Reporter: lylavoie@iol.unh.edu CC: dpdklab@iol.unh.edu Target Milestone: --- A DPDK user has reported an issue where, some hardware may have issues with freeing resources overflows occur due to attempts to exceed the packet throughput limitations of the hardware / systems. Below is the full email change. Outcome: Develop test case in DTS to specifically check this condition (i.e attempt to exceed the capacity, then check for a "return" to the original baseline). 18/02/2020 09:36, Hrvoje Habjanic: > On 08. 04. 2019. 11:52, Hrvoje Habjani=C4=87 wrote: > > On 29/03/2019 08:24, Hrvoje Habjani=C4=87 wrote: > >>> Hi. > >>> > >>> I did write an application using dpdk 17.11 (did try also with 18.11), > >>> and when doing some performance testing, i'm seeing very odd behavior. > >>> To verify that this is not because of my app, i did the same test with > >>> l2fwd example app, and i'm still confused by results. > >>> > >>> In short, i'm trying to push a lot of L2 packets through dpdk engine - > >>> packet processing is minimal. When testing, i'm starting with small > >>> number of packets-per-second, and then gradually increase it to see > >>> where is the limit. At some point, i do reach this limit - packets st= art > >>> to get dropped. And this is when stuff become weird. > >>> > >>> When i reach peek packet rate (at which packets start to get dropped)= , i > >>> would expect that reducing packet rate will remove packet drops. But, > >>> this is not the case. For example, let's assume that peek packet rate= is > >>> 3.5Mpps. At this point everything works ok. Increasing pps to 4.0Mpps, > >>> makes a lot of dropped packets. When reducing pps back to 3.5Mpps, app > >>> is still broken - packets are still dropped. > >>> > >>> At this point, i need to drastically reduce pps (1.4Mpps) to make > >>> dropped packets go away. Also, app is unable to successfully forward > >>> anything beyond this 1.4M, despite the fact that in the beginning it = did > >>> forward 3.5M! Only way to recover is to restart the app. > >>> > >>> Also, sometimes, the app just stops forwarding any packets - packets = are > >>> received (as seen by counters), but app is unable to send anything ba= ck. > >>> > >>> As i did mention, i'm seeing the same behavior with l2fwd example app= . I > >>> did test dpdk 17.11 and also dpdk 18.11 - the results are the same. > >>> > >>> My test environment is HP DL380G8, with 82599ES 10Gig (ixgbe) cards, > >>> connected with Cisco nexus 9300 sw. On the other side is ixia test > >>> appliance. Application is run in virtual machine (VM), using KVM > >>> (openstack, with sriov enabled, and numa restrictions). I did check t= hat > >>> VM is using only cpu's from NUMA node on which network card is > >>> connected, so there is no cross-numa traffic. Openstack is Queens, > >>> Ubuntu is Bionic release. Virtual machine is also using ubuntu bionic > >>> as OS. > >>> > >>> I do not know how to debug this? Does someone else have the same > >>> observations? > >>> > >>> Regards, > >>> > >>> H. > >> There are additional findings. It seems that when i reach peak pps > >> rate, application is not fast enough, and i can see rx missed errors > >> on card statistics on the host. At the same time, tx side starts to > >> show problems (tx burst starts to show it did not send all packets). > >> Shortly after that, tx falls apart completely and top pps rate drops. > >> > >> Since i did not disable pause frames, i can see on the switch "RX > >> pause" frame counter is increasing. On the other hand, if i disable > >> pause frames (on the nic of server), host driver (ixgbe) reports "TX > >> unit hang" in dmesg, and issues card reset. Of course, after reset > >> none of the dpdk apps in VM's on this host does not work. > >> > >> Is it possible that at time of congestion DPDK does not release mbufs > >> back to the pool, and tx ring becomes "filled" with zombie packets > >> (not send by card and also having ref counter as they are in use)? > >> > >> Is there a way to check mempool or tx ring for "left-owers"? Is is > >> possible to somehow "flush" tx ring and/or mempool? > >> > >> H. > > After few more test, things become even weirder - if i do not free mbufs > > which are not sent, but resend them again, i can "survive" over-the-peek > > event! But, then peek rate starts to drop gradually ... > > > > I would ask if someone can try this on their platform and report back? I > > would really like to know if this is problem with my deployment, or > > there is something wrong with dpdk? > > > > Test should be simple - use l2fwd or l3fwd, and determine max pps. Then > > drive pps 30%over max, and then return back and confirm that you can > > still get max pps. > > > > Thanks in advance. > > > > H. > > > > I did receive few mails from users facing this issue, asking how it was > resolved. > > Unfortunately, there is no real fix. It seems that this issue is related > to card and hardware used. I'm still not sure which is more to blame, > but the combination i had is definitely problematic. > > Anyhow, in the end, i did conclude that card driver have some issues > when it is saturated with packets. My suspicion is that driver/software > does not properly free packets, and then DPDK mempool becomes > fragmented, and this causes performance drops. Restarting software > releases pools, and restores proper functionality. > > After no luck with ixgbe, we migrated to Mellanox (4LX), and now there > is no more of this permanent performance drop. With mlx, when limit is > reached, reducing number of packets restores packet forwarding, and this > limit seems to be stable. > > Also, we moved to newer servers - DL380G10, and got significant > performance increase. Also, we moved to newer switch (also cisco), with > 25G ports, which reduced latency - almost by factor of 2! > > I did not try old ixgbe on newer server, but i did try Intel's XL710, > and it is not as happy as Mellanox. It gives better PPS, but it is more > unstable in terms of maximum bw (has similar issues as ixgbe). > > Regards, > > H. --=20 You are receiving this mail because: You are the assignee for the bug.=