From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932146Ab2B1ADI (ORCPT ); Mon, 27 Feb 2012 19:03:08 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:47873 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756269Ab2B1ADD (ORCPT ); Mon, 27 Feb 2012 19:03:03 -0500 Date: Mon, 27 Feb 2012 16:03:02 -0800 From: Andrew Morton To: "Jan Beulich" Cc: Subject: Re: [PATCH v2] consolidate WARN_...ONCE() static variables Message-Id: <20120227160302.ef9f6af4.akpm@linux-foundation.org> In-Reply-To: <4F4BAAFA0200007800074F8F@nat28.tlf.novell.com> References: <4F4BAAFA0200007800074F8F@nat28.tlf.novell.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 27 Feb 2012 15:10:34 +0000 "Jan Beulich" wrote: > Due to the alignment of following variables, these typically consume > more than just the single byte that 'bool' requires, and as there are > a few hundred instances, the cache pollution (not so much the waste of > memory) sums up. Put these variables into their own section, outside > of any half way frequently used memory range. > > v2: Do the same also to the __warned variable of rcu_lockdep_assert(). > (Don't, however, include the ones used by printk_once() and alike, as > they can potentially be hot.) I have a bad feeling that I still don't understand this patch. Ho hum. What are the rules for the new .data.unlikely section? When should people put variables into this section? Perhaps we can document this somewhere?