From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754138AbaCCJLu (ORCPT ); Mon, 3 Mar 2014 04:11:50 -0500 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:59420 "EHLO e06smtp12.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753997AbaCCJLr (ORCPT ); Mon, 3 Mar 2014 04:11:47 -0500 Message-ID: <53144747.2070605@de.ibm.com> Date: Mon, 03 Mar 2014 10:11:35 +0100 From: Christian Borntraeger User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Vlad Yasevich , vyasevic@redhat.com CC: "David S. Miller" , Jason Wang , "Michael S. Tsirkin" , netdev@vger.kernel.org, KVM list , Linux Kernel Mailing List Subject: Re: macvtap performance regression (bisected) between 3.13 and 3.14-rc1 References: <530FA586.3010400@de.ibm.com> <53110A62.7070109@redhat.com> <5311C142.6040509@de.ibm.com> <53123495.7030902@gmail.com> In-Reply-To: <53123495.7030902@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14030309-8372-0000-0000-000008DA85DA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/03/14 20:27, Vlad Yasevich wrote: > On 03/01/2014 06:15 AM, Christian Borntraeger wrote: >> On 28/02/14 23:14, Vlad Yasevich wrote: >>> On 02/27/2014 03:52 PM, Christian Borntraeger wrote: >>>> Vlad, >>>> >>>> commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523 >>>> macvtap: Add support of packet capture on macvtap device. >>>> >>>> causes a performance regression for iperf traffic between two KVM guests >>>> on my s390 system. Both guests are connected via two macvtaps on the same OSA >>>> network card. >>>> Before that patch I get ~20 Gbit/sec between two guests, afterwards I get >>>> ~4Gbit/sec >>>> >>>> Latency seems to be unchanges (uperf 1byte ping pong). >>>> >>>> According to ifconfig in the guest, I have ~ 1500 bytes per packet with this >>>> patch and ~ 40000 bytes without. So for some reason this patch causes the >>>> network stack to do segmentation. (the guest kernel stays the same, only host >>>> kernel is changed). >>>> >>>> Any ideas? >>> >>> I am looking. It shouldn't cause addition segmentations and when I ran >>> netperf on the code I didn't see any difference in the throughput. >> >> Dont know if the different bytes/packets ratio is really the reason or >> just a side effect. As a hint: the underlying network device does not support >> segmentation, but this should not matter for traffic between to guests. > > Could you post 'ethtool -k' output for both lower-level device and the > macvtap device? Features for eth0: rx-checksumming: off [fixed] tx-checksumming: off tx-checksum-ipv4: off [fixed] tx-checksum-ip-generic: off [fixed] tx-checksum-ipv6: off [fixed] tx-checksum-fcoe-crc: off [fixed] tx-checksum-sctp: off [fixed] scatter-gather: off tx-scatter-gather: off [fixed] tx-scatter-gather-fraglist: off [fixed] tcp-segmentation-offload: off tx-tcp-segmentation: off [fixed] tx-tcp-ecn-segmentation: off [fixed] tx-tcp6-segmentation: off [fixed] udp-fragmentation-offload: off [fixed] generic-segmentation-offload: off [requested on] generic-receive-offload: on large-receive-offload: off [fixed] rx-vlan-offload: off [fixed] tx-vlan-offload: off [fixed] ntuple-filters: off [fixed] receive-hashing: off [fixed] highdma: off [fixed] rx-vlan-filter: on [fixed] vlan-challenged: off [fixed] tx-lockless: off [fixed] netns-local: off [fixed] tx-gso-robust: off [fixed] tx-fcoe-segmentation: off [fixed] tx-gre-segmentation: off [fixed] tx-ipip-segmentation: off [fixed] tx-sit-segmentation: off [fixed] tx-udp_tnl-segmentation: off [fixed] tx-mpls-segmentation: off [fixed] fcoe-mtu: off [fixed] tx-nocache-copy: off loopback: off [fixed] rx-fcs: off [fixed] rx-all: off [fixed] tx-vlan-stag-hw-insert: off [fixed] rx-vlan-stag-hw-parse: off [fixed] rx-vlan-stag-filter: off [fixed] l2-fwd-offload: off [fixed] Features for macvtap1: rx-checksumming: off [fixed] tx-checksumming: off tx-checksum-ipv4: off [fixed] tx-checksum-ip-generic: off [fixed] tx-checksum-ipv6: off [fixed] tx-checksum-fcoe-crc: off [fixed] tx-checksum-sctp: off [fixed] scatter-gather: off tx-scatter-gather: off [fixed] tx-scatter-gather-fraglist: off [fixed] tcp-segmentation-offload: off tx-tcp-segmentation: off [fixed] tx-tcp-ecn-segmentation: off [fixed] tx-tcp6-segmentation: off [fixed] udp-fragmentation-offload: off [fixed] generic-segmentation-offload: off [requested on] generic-receive-offload: on large-receive-offload: off [fixed] rx-vlan-offload: off [fixed] tx-vlan-offload: off [fixed] ntuple-filters: off [fixed] receive-hashing: off [fixed] highdma: off [fixed] rx-vlan-filter: on [fixed] vlan-challenged: off [fixed] tx-lockless: on [fixed] netns-local: off [fixed] tx-gso-robust: off [fixed] tx-fcoe-segmentation: off [fixed] tx-gre-segmentation: off [fixed] tx-ipip-segmentation: off [fixed] tx-sit-segmentation: off [fixed] tx-udp_tnl-segmentation: off [fixed] tx-mpls-segmentation: off [fixed] fcoe-mtu: off [fixed] tx-nocache-copy: off loopback: off [fixed] rx-fcs: off [fixed] rx-all: off [fixed] tx-vlan-stag-hw-insert: off [fixed] rx-vlan-stag-hw-parse: off [fixed] rx-vlan-stag-filter: off [fixed] l2-fwd-offload: off [fixed]