From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 094CB6B0044 for ; Fri, 18 Dec 2009 13:45:27 -0500 (EST) Date: Fri, 18 Dec 2009 19:45:04 +0100 From: Ingo Molnar 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: Sender: owner-linux-mm@kvack.org 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 List-ID: * 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, 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