From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: RFC: NAPI packet weighting patch Date: Mon, 06 Jun 2005 17:08:57 -0700 Message-ID: <42A4E599.2090604@candelatech.com> References: <468F3FDA28AA87429AD807992E22D07E0450C00B@orsmsx408> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "Ronciak, John" , "David S. Miller" , mchan@broadcom.com, hadi@cyberus.ca, buytenh@wantstofly.org, jdmason@us.ibm.com, shemminger@osdl.org, netdev@oss.sgi.com, Robert.Olsson@data.slu.se, "Venkatesan, Ganesh" , "Brandeburg, Jesse" Return-path: To: Mitch Williams In-Reply-To: Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Mitch Williams wrote: > > On Mon, 6 Jun 2005, Ronciak, John wrote: > > >>> If you force the e1000 driver to do RX replenishment every N >>> packets it should reduce the packet drops the same (in the >>> single NIC case) as if you reduced the dev->weight to that >>> same value N. >> >>But this isn't what we are seeing. Even if we just reduce the weight >>value to 32 from 64, all of the drops go away. So there seems to be >>other things affecting this. > > > Some quickie results for everybody -- I've been working on other stuff this > morning and haven't had much time in the lab. > > Increasing the RX ring to 512 descriptors eliminates dropped packets, but > performance goes down. When I mentioned this, John and Jesse both nodded > and said, "Yep. That's what happens when the descriptor ring grows past > one page." > > Reducing the weight to 32 got rid of almost all of the dropped packets > (down to < 1 per second); reducing it to 20 eliminated all of them. In > both cases performance rose as compared to the default weight of 64. > > Tests were run on 2.6.12rc5 on a dual Xeon 2.8GHz PCI-X system. We run > Chariot for performance testing, using TCP/IP large file transfers with 10 > Windows 2000 clients. So is the Linux server reading/writing these large files to/from the disk? Can you tell us how much performance went down when you increased the descriptors to 512? Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com