Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756655AbXELKBy (ORCPT ); Sat, 12 May 2007 06:01:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755466AbXELKBr (ORCPT ); Sat, 12 May 2007 06:01:47 -0400 Received: from viefep13-int.chello.at ([213.46.255.15]:55358 "EHLO viefep15-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755327AbXELKBr (ORCPT ); Sat, 12 May 2007 06:01:47 -0400 Subject: Re: [PATCH 0/2] convert mmap_sem to a scalable rw_mutex From: Peter Zijlstra To: Esben Nielsen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oleg Nesterov , Andrew Morton , Ingo Molnar , Thomas Gleixner , Nick Piggin In-Reply-To: References: <20070511131541.992688403@chello.nl> Content-Type: text/plain Date: Sat, 12 May 2007 12:01:43 +0200 Message-Id: <1178964103.6810.55.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 819 Lines: 22 On Sat, 2007-05-12 at 11:27 +0200, Esben Nielsen wrote: > > On Fri, 11 May 2007, Peter Zijlstra wrote: > > > > > I was toying with a scalable rw_mutex and found that it gives ~10% reduction in > > system time on ebizzy runs (without the MADV_FREE patch). > > > > You break priority enheritance on user space futexes! :-( > The problems is that the futex waiter have to take the mmap_sem. And as > your rw_mutex isn't PI enabled you get priority inversions :-( Do note that rwsems have no PI either. PI is not a concern for mainline - yet, I do have ideas here though. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/