From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: KVM VM(rhel-5.5) %si is too high when TX/RX packets Date: Sat, 04 May 2013 09:48:05 +0200 Message-ID: <5184BD35.2000207@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm list , "linux-kernel@vger.kernel.org" , qemu-devel , Luonengjun , Zanghongyong , "Huangweidong (C)" , Qinchuanyu To: "Zhanghaoyu (A)" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:34105) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UYXCW-0008B6-1e for qemu-devel@nongnu.org; Sat, 04 May 2013 03:48:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UYXCV-0003sA-8D for qemu-devel@nongnu.org; Sat, 04 May 2013 03:48:11 -0400 Received: from mail-ee0-f54.google.com ([74.125.83.54]:61524) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UYXCV-0003s4-0v for qemu-devel@nongnu.org; Sat, 04 May 2013 03:48:11 -0400 Received: by mail-ee0-f54.google.com with SMTP id e49so1078903eek.13 for ; Sat, 04 May 2013 00:48:09 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <5184BD35.2000207@redhat.com> Date: Sat, 04 May 2013 09:48:05 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] KVM VM(rhel-5.5) %si is too high when TX/RX packets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Zhanghaoyu (A)" Cc: "Huangweidong (C)" , kvm list , Luonengjun , "linux-kernel@vger.kernel.org" , qemu-devel , Zanghongyong , Qinchuanyu 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