Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757366Ab3EDHsN (ORCPT ); Sat, 4 May 2013 03:48:13 -0400 Received: from mail-ea0-f179.google.com ([209.85.215.179]:38414 "EHLO mail-ea0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755082Ab3EDHsL (ORCPT ); Sat, 4 May 2013 03:48:11 -0400 Message-ID: <5184BD35.2000207@redhat.com> Date: Sat, 04 May 2013 09:48:05 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: "Zhanghaoyu (A)" CC: kvm list , "linux-kernel@vger.kernel.org" , qemu-devel , Luonengjun , Zanghongyong , "Huangweidong (C)" , Qinchuanyu Subject: Re: KVM VM(rhel-5.5) %si is too high when TX/RX packets References: In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1785 Lines: 23 Il 03/05/2013 06:05, Zhanghaoyu (A) ha scritto: > I running a VM(RHEL-5.5) on KVM hypervisor(linux-3.8 + QEMU-1.4.1), and direct-assign intel 82576 VF to the VM. When TX/RX packets on VM to the other host via iperf tool, top tool result on VM shown that the %si is too high, approximately 95% ~ 100%, but from the view of host, the VM's total CPU usage is about 20% - 30%. And the throughput rate is approximately 200Mb/s, far from the line rate 1Gb/s, > And, I found the hardirq rate is lower than normal by running "watch -d -n 1 cat /proc/interrupts", I think it's caused by the too high %si, because the NIC's hardirq was disabled during the softirq process. > Then, I direct-assign the intel 82576 to the VM, the same case happened too. > I found the intel 82576 and intel 82576 VF's interrupt mode are both PCI-MSI-X. > > And, > I rmmod the igb driver, and, re-insmod the igb driver(igb-4.1.2) with the parameter IntMode=0/1(0:legacy, 1:MSI, 2:MSI-x), the problem then gone, the %si is approximately 20% -30%, and the throughput rate came to the line rate, about 940Mb/s. > I update the VM to RHEL-6.1, the problem disappeared too. > And, I found a very strange thing, the VM's 82576VF's irq routing is set one time on Vf's one interrupt received, so frequently. RHEL 5.5 is a very old update. Can you try RHEL 5.9? In any case, this looks a lot like a bug in the version of the driver that was included in RHEL5.5; you should contact Red Hat support services if you can still reproduce it with the latest RHEL5 update. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/