From mboxrd@z Thu Jan 1 00:00:00 1970 From: linas@austin.ibm.com (Linas Vepstas) Subject: Re: [PATCH 1/2]: powerpc/cell spidernet bottom half Date: Wed, 16 Aug 2006 18:47:28 -0500 Message-ID: <20060816234728.GP20551@austin.ibm.com> References: <44E34825.2020105@garzik.org> <200608162324.47235.arnd@arndb.de> <20060816225558.GM20551@austin.ibm.com> <200608170103.21097.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linuxppc-dev@ozlabs.org, akpm@osdl.org, jeff@garzik.org, netdev@vger.kernel.org, jklewis@us.ibm.com, linux-kernel@vger.kernel.org, Jens.Osterkamp@de.ibm.com, David Miller Return-path: Received: from e36.co.us.ibm.com ([32.97.110.154]:33439 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S932123AbWHPXsa (ORCPT ); Wed, 16 Aug 2006 19:48:30 -0400 To: Arnd Bergmann Content-Disposition: inline In-Reply-To: <200608170103.21097.arnd@arndb.de> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Aug 17, 2006 at 01:03:20AM +0200, Arnd Bergmann wrote: > > Could well be related to latencies when going to the remote > node for descriptor DMAs. Have you tried if the hch's NUMA > patch or using numactl makes a difference here? No. I guess I should try. > > > sounds like the right approach to simplify the code. > > > > Its not a big a driver. 'wc' says its 2.3 loc, which > > is 1/3 or 1/5 the size of tg3.c or the e1000*c files. > > Right, I was thinking of removing a lock or another, not > throwing out half of the driver ;-) There's only four lock points grand total. -- One on the receive side, -- one to protect the transmit head pointer, -- one to protect the transmit tail pointer, -- one to protect the location of the transmit low watermark. The last three share the same lock. I tried using distinct locks, but this worsened things, probably due to cache-line trashing. I tried removing the head pointer lock, but this failed. I don't know why, and was surprised by this. I thought hard_start_xmit() was serialized. --linas