From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx174.postini.com [74.125.245.174]) by kanga.kvack.org (Postfix) with SMTP id 7EE626B0033 for ; Fri, 14 Jun 2013 18:47:14 -0400 (EDT) Received: by mail-ie0-f181.google.com with SMTP id x12so2671303ief.12 for ; Fri, 14 Jun 2013 15:47:13 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1371249104.1758.20.camel@buesod1.americas.hpqcorp.net> References: <1371165333.27102.568.camel@schen9-DESK> <1371167015.1754.14.camel@buesod1.americas.hpqcorp.net> <1371226197.27102.594.camel@schen9-DESK> <1371249104.1758.20.camel@buesod1.americas.hpqcorp.net> Date: Fri, 14 Jun 2013 15:47:13 -0700 Message-ID: Subject: Re: Performance regression from switching lock to rw-sem for anon-vma tree From: Michel Lespinasse Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Davidlohr Bueso Cc: Tim Chen , Ingo Molnar , Rik van Riel , Peter Zijlstra , Andrea Arcangeli , Mel Gorman , "Shi, Alex" , Andi Kleen , Andrew Morton , "Wilcox, Matthew R" , Dave Hansen , linux-kernel@vger.kernel.org, linux-mm On Fri, Jun 14, 2013 at 3:31 PM, Davidlohr Bueso wrote: > A few ideas that come to mind are avoiding taking the ->wait_lock and > avoid dealing with waiters when doing the optimistic spinning (just like > mutexes do). > > I agree that we should first deal with the optimistic spinning before > adding the MCS complexity. Maybe it would be worth disabling the MCS patch in mutex and comparing that to the rwsem patches ? Just to make sure the rwsem performance delta isn't related to that. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- 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