From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f181.google.com (mail-pd0-f181.google.com [209.85.192.181]) by kanga.kvack.org (Postfix) with ESMTP id 9F91F6B0031 for ; Tue, 24 Sep 2013 23:32:22 -0400 (EDT) Received: by mail-pd0-f181.google.com with SMTP id g10so5439232pdj.40 for ; Tue, 24 Sep 2013 20:32:22 -0700 (PDT) Message-ID: <1380079935.2163.3.camel@buesod1.americas.hpqcorp.net> Subject: Re: [PATCH v5 0/6] rwsem: performance optimizations From: Davidlohr Bueso Date: Tue, 24 Sep 2013 20:32:15 -0700 In-Reply-To: <1380061341.3467.49.camel@schen9-DESK> References: <1380061341.3467.49.camel@schen9-DESK> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tim Chen Cc: Ingo Molnar , Andrew Morton , Andrea Arcangeli , Alex Shi , Andi Kleen , Michel Lespinasse , Davidlohr Bueso , Matthew R Wilcox , Dave Hansen , Peter Zijlstra , Rik van Riel , Peter Hurley , linux-kernel@vger.kernel.org, linux-mm On Tue, 2013-09-24 at 15:22 -0700, Tim Chen wrote: > We have incorporated various suggestions from Ingo for version 5 of this patchset > and will like to have it merged if there are no objections. > > In this patchset, we introduce two categories of optimizations to read > write semaphore. The first four patches from Alex Shi reduce cache bouncing of the > sem->count field by doing a pre-read of the sem->count and avoid cmpxchg > if possible. > > The last two patches introduce similar optimistic spinning logic as > the mutex code for the writer lock acquisition of rwsem. Right. We address the general 'mutexes out perform writer-rwsems' situations that has been seen in more than one case. Users now need not worry about performance issues when choosing between these two locking mechanisms. Thanks, Davidlohr -- 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