From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH v9 00/16] Provide a zero-copy method on KVM virtio-net. Date: Fri, 3 Sep 2010 13:14:37 +0300 Message-ID: <20100903101437.GA31575@redhat.com> References: <1281086624-5765-1-git-send-email-xiaohui.xin@intel.com> <1281489804.3391.23.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: xiaohui.xin@intel.com, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, davem@davemloft.net, herbert@gondor.hengli.com.au, jdike@linux.intel.com To: Shirley Ma Return-path: Received: from mx1.redhat.com ([209.132.183.28]:54987 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755154Ab0ICKUt (ORCPT ); Fri, 3 Sep 2010 06:20:49 -0400 Content-Disposition: inline In-Reply-To: <1281489804.3391.23.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Aug 10, 2010 at 06:23:24PM -0700, Shirley Ma wrote: > Hello Xiaohui, > > On Fri, 2010-08-06 at 17:23 +0800, xiaohui.xin@intel.com wrote: > > Our goal is to improve the bandwidth and reduce the CPU usage. > > Exact performance data will be provided later. > > Have you had any performance data to share here? I tested my > experimental macvtap zero copy for TX only. The performance I have seen > as below without any tuning, (default setting): > > Before: netperf 16K message size results with 60 secs run is 7.5Gb/s > over ixgbe 10GbE card. perf top shows: > > 2103.00 12.9% copy_user_generic_string > 1541.00 9.4% handle_tx > 1490.00 9.1% _raw_spin_unlock_irqrestore > 1361.00 8.3% _raw_spin_lock_irqsave > 1288.00 7.9% _raw_spin_lock > 924.00 5.7% vhost_worker > > After: netperf results with 60 secs run is 8.1Gb/s, perf output: > > 1093.00 9.9% _raw_spin_unlock_irqrestore > 1048.00 9.5% handle_tx > 934.00 8.5% _raw_spin_lock_irqsave > 864.00 7.9% _raw_spin_lock > 644.00 5.9% vhost_worker > 387.00 3.5% use_mm > > I am still working on collecting more data (latency, cpu > utilization...). I will let you know once I get all data for macvtap TX > zero copy. Also I found some vhost performance regression on the new > kernel with tuning. I used to get 9.4Gb/s, now I couldn't get it. > > Shirley Could you please try disabling mergeable buffers, and see if this gets you back where you were? -global virtio-net-pci.mrg_rxbuf=off -- MST