From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: Re: Regression: too many packets with incorrect checksum Date: Thu, 09 May 2013 17:17:43 +0800 Message-ID: <1368091063.12413.9.camel@cr0> References: <1368013888.3115.9.camel@cr0> <1368088578.12413.4.camel@cr0> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "David S. Miller" To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:13643 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752698Ab3EIJRs (ORCPT ); Thu, 9 May 2013 05:17:48 -0400 In-Reply-To: <1368088578.12413.4.camel@cr0> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2013-05-09 at 16:36 +0800, Cong Wang wrote: > > Running another RHEL6 KVM guest, it doesn't have this problem, so it is > not related with KVM environment. I thought it might be due to tcpdump receives a packet which is checksummed partially while the wire receives a correct one, but netperf shows that is wrong, apparently it hurts performance: With latest -net: ~% netperf -4 -H 192.168.122.74 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.122.74 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.20 105.19 With a RHEL6 kernel: ~% netperf -4 -H 192.168.122.101 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.122.101 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.00 5528.64