From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shirley Ma Subject: Re: Network performance with small packets Date: Thu, 03 Feb 2011 07:58:00 -0800 Message-ID: <1296748680.25430.169.camel@localhost.localdomain> References: <20110202154706.GA12738@redhat.com> <1296666635.25430.35.camel@localhost.localdomain> <20110202173213.GA13907@redhat.com> <1296670311.25430.49.camel@localhost.localdomain> <20110202182720.GB14257@redhat.com> <1296674975.25430.59.camel@localhost.localdomain> <20110202201731.GB15150@redhat.com> <1296680585.25430.98.camel@localhost.localdomain> <20110202212047.GD15150@redhat.com> <1296709556.25430.140.camel@localhost.localdomain> <20110203061326.GC22230@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Krishna Kumar2 , David Miller , kvm@vger.kernel.org, mashirle@linux.vnet.ibm.com, netdev@vger.kernel.org, netdev-owner@vger.kernel.org, Sridhar Samudrala , Steve Dobbelstein To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20110203061326.GC22230@redhat.com> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 2011-02-03 at 08:13 +0200, Michael S. Tsirkin wrote: > > Initial TCP_STREAM performance results I got for guest to local > host > > 4.2Gb/s for 1K message size, (vs. 2.5Gb/s) > > 6.2Gb/s for 2K message size, and (vs. 3.8Gb/s) > > 9.8Gb/s for 4K message size. (vs.5.xGb/s) > > What is the average packet size, # bytes per ack, and the # of > interrupts > per packet? It could be that just slowing down trahsmission > makes GSO work better. There is no TX interrupts with dropping packet. GSO/TSO is the key for small message performance, w/o GSO/TSO, the performance is limited to about 2Gb/s no matter how big the message size it is. I think any work we try here will increase large packet size rate. BTW for dropping packet, TCP increased fast retrans, not slow start. I will collect tcpdump, netstart before and after data to compare packet size/rate w/o w/i the patch. Thanks Shirley