From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753583Ab3B0WQO (ORCPT ); Wed, 27 Feb 2013 17:16:14 -0500 Received: from mail-pa0-f54.google.com ([209.85.220.54]:60375 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752460Ab3B0WQK (ORCPT ); Wed, 27 Feb 2013 17:16:10 -0500 Date: Wed, 27 Feb 2013 14:16:07 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Michal Hocko cc: Andrew Morton , Mel Gorman , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch] mm, show_mem: suppress page counts in non-blockable contexts In-Reply-To: <20130227100024.GA16724@dhcp22.suse.cz> Message-ID: References: <20130227100024.GA16724@dhcp22.suse.cz> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 27 Feb 2013, Michal Hocko wrote: > But we are trying to prevent from soft lockups by calling > touch_nmi_watchdog every now when iterating over pages so the lock up > detector shouldn't trigger. > > Anyway, I think that the additional information (which can be really > costly as you are describing) is not that useful. Most of the useful > information is already printed by show_free_areas. Or does it help when > we know how much memory is shared/reserved/etc. when the allocation > fails? > I do not think it is helpful since show_free_areas() already shows all pertinent information, and hence I'm suppressing it in atomic contexts in this patch. > So I do agree with the dropping the additional information for the > allocation failure path (sysrq+m might still show it) but I fail to see > how the lockup detector plays any role here. Can we just drop it because > it is not that interesting and it is costly so it is not worth > bothering? > I would agree it is not interesting to debugging VM issues and is obviously very expensive.