From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755373Ab1ATKnp (ORCPT ); Thu, 20 Jan 2011 05:43:45 -0500 Received: from canuck.infradead.org ([134.117.69.58]:46693 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752071Ab1ATKnn convert rfc822-to-8bit (ORCPT ); Thu, 20 Jan 2011 05:43:43 -0500 Subject: Re: [PATCH -v10 0/4] Lock-less list From: Peter Zijlstra To: Andrew Morton Cc: Huang Ying , "linux-kernel@vger.kernel.org" , Andi Kleen , Linus Torvalds , Ingo Molnar , Chris Mason In-Reply-To: <20110119165247.cca2f434.akpm@linux-foundation.org> References: <1295245019-7816-1-git-send-email-ying.huang@intel.com> <20110119135546.bb7e8f62.akpm@linux-foundation.org> <1295484358.15213.25.camel@yhuang-dev> <20110119165247.cca2f434.akpm@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 20 Jan 2011 11:44:07 +0100 Message-ID: <1295520247.28776.152.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-01-19 at 16:52 -0800, Andrew Morton wrote: > On Thu, 20 Jan 2011 08:45:58 +0800 > Huang Ying wrote: > > > On Thu, 2011-01-20 at 05:55 +0800, Andrew Morton wrote: > > > I'm trying to remember why we're talking about this. > > > > > > You had an ACPI-based "hardware error reporting" thing. And that > > > required an nmi-context memory allocator. And that required a > > > "lockless" list implementation. > > > > > > Yes? > > > > Yes. But the "lockless" list implementation is general, it can be used > > by other part of kernel too, such as irq_work and xlist in > > net/rds/xlist.h in the patchset. > > Well. Lots of things are general but that doesn't mean we toss them > into the kernel when we already have plenty of infrastructure to handle > that sort of thing. > > otoh, hoisting xlist.h out of net/rds and making it generally available > is a good thing. > > otooh, net/rds/ probably didn't need xlist at all and could have used > existing general code. > > So... I'd say that unless and until the NMI-context allocator is > merged, the case for merging the lockless list code is a bit marginal? > Or have you identified other code sites which could use llist and which > would gain some benefit from migrating? In fact, I have a patch ready and waiting to revert the whole irq_work stuff, that too seems to be a superfluous generalization.