From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 19 Sep 2001 19:25:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 19 Sep 2001 19:25:32 -0400 Received: from t2.redhat.com ([199.183.24.243]:15357 "HELO executor.cambridge.redhat.com") by vger.kernel.org with SMTP id ; Wed, 19 Sep 2001 19:25:16 -0400 To: Andrea Arcangeli Cc: David Howells , Linus Torvalds , Manfred Spraul , Ulrich.Weigand@de.ibm.com, linux-kernel@vger.kernel.org Subject: Re: Deadlock on the mm->mmap_sem In-Reply-To: Message from Andrea Arcangeli of "Wed, 19 Sep 2001 20:47:20 +0200." <20010919204720.L720@athlon.random> Date: Thu, 20 Sep 2001 00:25:40 +0100 Message-ID: <7486.1000941940@warthog.cambridge.redhat.com> From: David Howells Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrea Arcangeli wrote: > On Wed, Sep 19, 2001 at 07:26:33PM +0100, David Howells wrote: > > > if we go generic then I strongly recommend my version of the generic > > > semaphores is _much_ faster (and cleaner) than this one > > > > Not so:-) Your patch, Andrea, grabs the spinlock far more than is necessary. > > then why your microbenchmarks says my version is much faster? They don't: [my rwsem-unfair-2.diff patch] #rds #wrs time : rd granted [spread] wr granted [spread] ==== ==== ===== =================== =================== 1 0 10s: 25384639 [0.008%] 0 [0.000%] 2 0 10s: 8007388 [0.013%] 0 [0.000%] 4 0 10s: 8004833 [0.007%] 0 [0.000%] 0 1 10s: 0 [0.000%] 25717288 [0.009%] 0 4 10s: 0 [0.000%] 2817293 [2.323%] 4 2 10s: 12742523 [0.008%] 114 [5.394%] 30 1 10s: 12739163 [0.002%] 92 [1.739%] 30 15 50s: 63733591 [0.003%] 286 [2.711%] [Andrea's 00_rwsem-19 patch] #rds #wrs time : rd granted [spread] wr granted [spread] ==== ==== ===== =================== =================== 1 0 10s: 24577938 [0.003%] 0 [0.000%] 2 0 10s: 5631224 [0.016%] 0 [0.000%] 4 0 10s: 5633280 [0.009%] 0 [0.000%] 0 1 10s: 0 [0.000%] 24572785 [0.007%] 0 4 10s: 0 [0.000%] 3444786 [0.091%] 4 2 10s: 8036291 [0.008%] 122 [4.918%] 30 1 10s: 8036490 [0.006%] 89 [1.253%] 30 15 50s: 40200472 [0.001%] 265 [2.717%] [Unpatched kernel] #rds #wrs time : rd granted [spread] wr granted [spread] ==== ==== ===== =================== =================== 1 0 10s: 30118903 [0.008%] 0 [0.000%] 2 0 10s: 12543737 [0.007%] 0 [0.000%] 4 0 10s: 12543731 [0.006%] 0 [0.000%] 0 1 10s: 0 [0.000%] 28408147 [0.008%] 0 4 10s: 0 [0.000%] 1554495 [0.172%] 4 2 10s: 1119656 [0.076%] 560020 [0.077%] 30 1 10s: 5361923 [0.024%] 55787 [0.012%] 30 15 50s: 5322473 [0.049%] 2661621 [0.050%] David