From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752248AbZAGMOj (ORCPT ); Wed, 7 Jan 2009 07:14:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753824AbZAGMOP (ORCPT ); Wed, 7 Jan 2009 07:14:15 -0500 Received: from hera.kernel.org ([140.211.167.34]:50540 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753197AbZAGMON (ORCPT ); Wed, 7 Jan 2009 07:14:13 -0500 Message-ID: <49649C65.6000706@kernel.org> Date: Wed, 07 Jan 2009 21:13:25 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.18 (X11/20081112) MIME-Version: 1.0 To: Ingo Molnar CC: travis@sgi.com, Rusty Russell , Linux Kernel Mailing List , "H. Peter Anvin" , Andrew Morton , Eric Biederman , steiner@sgi.com, Hugh Dickins Subject: Re: regarding the x86_64 zero-based percpu patches References: <49649814.4040005@kernel.org> <20090107120225.GA30651@elte.hu> In-Reply-To: <20090107120225.GA30651@elte.hu> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 07 Jan 2009 12:13:29 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (cc'ing people from the original thread and LKML as it seems to require actual discussion.) Hello, this thread started with me asking for help regarding the zero-based percpu patches and the initial message is quoted below. Ingo Molnar wrote: > * Tejun Heo wrote: > >> Hello, Mike, Ingo. >> >> I was working on something which requires better dynamic per-cpu >> performance and have been working on implementing it myself but >> realized the strange gcc stack protector ABI limitation and with >> Rusty's hint and googling found out that Mike already did the heavy >> lifting. >> >> I read the "x86_64: Optimize percpu accesses" from July last year and >> it looks like it got stuck on tool chain problem which showed up as >> two problems (is one of the two resolved?). >> >> * Notifier call chain corruption >> >> * Stack overflow with default stack size >> >> >From the cpu_alloc thread from November, it seems Mike is quite >> pre-occupied, so I'm willing to give it a shot as it's blocking stuff >> I have in queue. The problem is that I'm having problem finding some >> information. >> >> 1. Mike seems to have splitted the patch but haven't posted them. >> >> 2. Ingo's x86/percpu-zerobased branch doesn't contain any revision not >> in the current upstream. Maybe the commits got lost during merges? >> >> 3. What failed and what got fixed and how to reproduce the problem. >> >> So, can you please help me a bit? I'll be happy to forward port the >> patches if they have bit-rotted. > > hm, i zapped them two days ago, because they collided with Rusty's ongoing > percpu-alloc work in his tree. Mike should be able to tell you what the > plans are for the resurrection of those patches. IIUC, Rusty is somewhat leaning toward limiting per-cpu area and using static allocator. (right?) As I was trying to do more stuff per-cpu (not putting a lot of stuff into per-cpu area but even with small things limited per-cpu area poses scalability problems), cpu_alloc seems to fit the bill better. Anyways, I think it's worthwhile to listen what people have on mind regarding how per-cpu stuff should proceed. Thanks. -- tejun