From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752379Ab3FRHNy (ORCPT ); Tue, 18 Jun 2013 03:13:54 -0400 Received: from mail-ie0-f172.google.com ([209.85.223.172]:63551 "EHLO mail-ie0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751031Ab3FRHNx (ORCPT ); Tue, 18 Jun 2013 03:13:53 -0400 MIME-Version: 1.0 In-Reply-To: References: <1371128589-8953-1-git-send-email-tangchen@cn.fujitsu.com> <1371128589-8953-17-git-send-email-tangchen@cn.fujitsu.com> <20130618015806.GY32663@mtj.dyndns.org> Date: Tue, 18 Jun 2013 00:13:52 -0700 X-Google-Sender-Auth: lSu6pDlHcpzP6rFKqIFtSLTuHzA Message-ID: Subject: Re: [Part1 PATCH v5 16/22] x86, mm, numa: Move numa emulation handling down. From: Yinghai Lu To: Tejun Heo Cc: Tang Chen , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrew Morton , Thomas Renninger , Jiang Liu , Wen Congyang , Lai Jiangshan , Yasuaki Ishimatsu , Mel Gorman , Minchan Kim , mina86@mina86.com, gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, Rik van Riel , jweiner@redhat.com, Prarit Bhargava , "the arch/x86 maintainers" , linux-doc@vger.kernel.org, Linux Kernel Mailing List , Linux MM , David Rientjes Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 17, 2013 at 11:22 PM, Yinghai Lu wrote: > On Mon, Jun 17, 2013 at 6:58 PM, Tejun Heo wrote: >> On Thu, Jun 13, 2013 at 09:03:03PM +0800, Tang Chen wrote: >>> From: Yinghai Lu >>> >>> numa_emulation() needs to allocate buffer for new numa_meminfo >>> and distance matrix, so execute it later in x86_numa_init(). >>> >>> Also we change the behavoir: >>> - before this patch, if user input wrong data in command >>> line, it will fall back to next numa probing or disabling >>> numa. >>> - after this patch, if user input wrong data in command line, >>> it will stay with numa info probed from previous probing, >>> like ACPI SRAT or amd_numa. >>> >>> We need to call numa_check_memblks to reject wrong user inputs early >>> so that we can keep the original numa_meminfo not changed. >> >> So, this is another very subtle ordering you're adding without any >> comment and I'm not sure it even makes sense because the function can >> fail after that point. > > Yes, if it fail, we will stay with current numa info from firmware. > That looks like right behavior. > > Before this patch, it will fail to next numa way like if acpi srat + user > input fail, it will try to go with amd_numa then try apply user info. > >> >> I'm getting really doubtful about this whole approach of carefully >> splitting discovery and registration. It's inherently fragile like >> hell and the poor documentation makes it a lot worse. I'm gonna reply >> to the head message. > > Maybe look at the patch is not clear enough, but if looks at the final changed > code it would be more clear. update the patches from 1-15 with your review. git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-x86-mm https://git.kernel.org/cgit/linux/kernel/git/yinghai/linux-yinghai.git/log/?h=for-x86-mm Yinghai