From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 0/9 Rev3] Implement batching skb API and support in IPoIB Date: Fri, 14 Sep 2007 10:24:35 -0700 (PDT) Message-ID: <20070914.102435.41643750.davem@davemloft.net> References: <20070826.190420.41652839.davem@davemloft.net> <1188257019.4250.55.camel@localhost> <20070914032055.8f96449b.billfink@mindspring.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: hadi@cyberus.ca, jheffner@psc.edu, rick.jones2@hp.com, krkumar2@in.ibm.com, gaagaan@gmail.com, general@lists.openfabrics.org, herbert@gondor.apana.org.au, jagana@us.ibm.com, jeff@garzik.org, johnpol@2ka.mipt.ru, kaber@trash.net, mcarlson@broadcom.com, mchan@broadcom.com, netdev@vger.kernel.org, peter.p.waskiewicz.jr@intel.com, rdreier@cisco.com, Robert.Olsson@data.slu.se, shemminger@linux-foundation.org, sri@us.ibm.com, tgraf@suug.ch, xma@us.ibm.com To: billfink@mindspring.com Return-path: Received: from 74-93-104-98-Washington.hfc.comcastbusiness.net ([74.93.104.98]:45588 "EHLO picasso.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752643AbXINRZx (ORCPT ); Fri, 14 Sep 2007 13:25:53 -0400 In-Reply-To: <20070914032055.8f96449b.billfink@mindspring.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Bill Fink Date: Fri, 14 Sep 2007 03:20:55 -0400 > TSO disabled performance is always better than equivalent TSO enabled > performance. With TSO enabled, the optimum performance is indeed at > a TX/RX interrupt coalescing value of 75 usec. With TSO disabled, > performance is the full 10-GigE line rate of 9910 Mbps for any value > of TX/RX interrupt coalescing from 15 usec to 105 usec. Note that the systems where the coalescing tweaking if often necessary are the heavily NUMA'd systems where cpu to device latency can be huge, like the big SGI ones which is where we had to tweak things in the tg3 driver in the first place. On most systems, as you saw mostly in the non-TSO case, the value choosen for the most part is arbitrary and not critical.