From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754052AbZHML4X (ORCPT ); Thu, 13 Aug 2009 07:56:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753885AbZHML4W (ORCPT ); Thu, 13 Aug 2009 07:56:22 -0400 Received: from brick.kernel.dk ([93.163.65.50]:57962 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753608AbZHML4W (ORCPT ); Thu, 13 Aug 2009 07:56:22 -0400 Date: Thu, 13 Aug 2009 13:56:23 +0200 From: Jens Axboe To: David Miller Cc: linux-kernel@vger.kernel.org, heiko.carstens@de.ibm.com Subject: Re: inlined spinlocks on sparc64 Message-ID: <20090813115623.GB12579@kernel.dk> References: <20090813082058.GX12579@kernel.dk> <20090813.020812.251047996.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090813.020812.251047996.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 13 2009, David Miller wrote: > From: Jens Axboe > Date: Thu, 13 Aug 2009 10:20:58 +0200 > > > I deleted the original thread, so I can't reply there. Just a heads up > > on the spinlock inlining on sparc64. I decided to give your patches a > > shot, since one of my IO benchmarks here basically degenerates into a > > spinlock microbenchmark with > 50% time spent there (unlock part, > > according to perf). Some of that is surely caching effects, but still. > > > > For this particular workload, I get a net improvement of about 3.5% with > > the inlined functions. Not bad. > > Doesn't surprise me, any function call can result in a register > window spill onto the stack, and that's 128 bytes of writes. > > Later when you leave the code path you have to refill that spilled > window and you get 128 bytes of reads for each one of those. Good thing it's not register starved ;-) Forgot to mention that it grew my kernel image by exactly 80KB, total size is around 5.5MB. -- Jens Axboe