From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by ug-out-1314.google.com with SMTP id s2so768676uge for ; Sat, 12 May 2007 02:27:41 -0700 (PDT) Date: Sat, 12 May 2007 11:27:13 +0200 (CEST) From: Esben Nielsen 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: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oleg Nesterov , Andrew Morton , Ingo Molnar , Thomas Gleixner , Nick Piggin List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org