Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932434AbZLRSps (ORCPT ); Fri, 18 Dec 2009 13:45:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754433AbZLRSpq (ORCPT ); Fri, 18 Dec 2009 13:45:46 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:55802 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754023AbZLRSpp (ORCPT ); Fri, 18 Dec 2009 13:45:45 -0500 Date: Fri, 18 Dec 2009 19:45:04 +0100 From: Ingo Molnar To: Christoph Lameter Cc: Avi Kivity , Peter Zijlstra , Andi Kleen , "Paul E. McKenney" , KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , minchan.kim@gmail.com Subject: Re: [mm][RFC][PATCH 0/11] mm accessor updates. Message-ID: <20091218184504.GA675@elte.hu> References: <20091217175338.GL9804@basil.fritz.box> <20091217190804.GB6788@linux.vnet.ibm.com> <20091217195530.GM9804@basil.fritz.box> <1261080855.27920.807.camel@laptop> <20091218051754.GC417@elte.hu> <4B2BB52A.7050103@redhat.com> <20091218171240.GB1354@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1316 Lines: 31 * Christoph Lameter wrote: > > We've been through this many times in the past within the kernel: many > > times when we hid some locking primitive within some clever wrapping > > scheme the quality of locking started to deteriorate. In most of the > > important cases we got rid of the indirection and went with an existing > > core kernel locking primitive which are all well known and have clear > > semantics and lead to more maintainable code. > > The existing locking APIs are all hiding lock details at various levels. We > have various specific APIs for specialized locks already Page locking etc. You need to loo at the patches. This is simply a step backwards: - up_read(&mm->mmap_sem); + mm_read_unlock(mm); because it hides the lock instance. ( You brought up -rt but that example does not apply: it doesnt 'hide' the lock instance in any way, it simply changes the preemption model. It goes to great lengths to keep existing locking patterns and does not obfuscate locking. ) Ingo -- 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/