Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758014AbXELJ1t (ORCPT ); Sat, 12 May 2007 05:27:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755327AbXELJ1n (ORCPT ); Sat, 12 May 2007 05:27:43 -0400 Received: from ug-out-1314.google.com ([66.249.92.172]:55974 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755073AbXELJ1m (ORCPT ); Sat, 12 May 2007 05:27:42 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=beta; h=received:date:from:x-x-sender:to:cc:subject:in-reply-to:message-id:references:mime-version:content-type; b=JzYOfDLoWmRTnwLCu8OtMv8EVj59FKCOyY9oNjf3PkhKK7CEcklLO0d2n8ZUu97bQe/02RvBzdwQZnTrhQQhqIf6ON9iM164bsB24rrDHOKs0WhGvTJ1yzR3whLgxHGn5Kp98BubiIJF04ONEojw5cmeDJKFj6MvOQycz4BuqVo= Date: Sat, 12 May 2007 11:27:13 +0200 (CEST) From: Esben Nielsen X-X-Sender: simlo@frodo.shire To: Peter Zijlstra cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oleg Nesterov , Andrew Morton , Ingo Molnar , Thomas Gleixner , Nick Piggin Subject: Re: [PATCH 0/2] convert mmap_sem to a scalable rw_mutex In-Reply-To: <20070511131541.992688403@chello.nl> Message-ID: References: <20070511131541.992688403@chello.nl> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 638 Lines: 19 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 :-( Esben - 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/