Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752863AbbKYPqO (ORCPT ); Wed, 25 Nov 2015 10:46:14 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:33248 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751958AbbKYPqK (ORCPT ); Wed, 25 Nov 2015 10:46:10 -0500 Date: Wed, 25 Nov 2015 16:46:07 +0100 From: Michal Hocko To: Peter Zijlstra Cc: Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Joonsoo Kim , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman Subject: Re: [PATCH v2 3/9] mm, page_owner: convert page_owner_inited to static key Message-ID: <20151125154607.GO27283@dhcp22.suse.cz> References: <1448368581-6923-1-git-send-email-vbabka@suse.cz> <1448368581-6923-4-git-send-email-vbabka@suse.cz> <20151125145202.GL27283@dhcp22.suse.cz> <5655CEDB.3040205@suse.cz> <20151125152533.GC17308@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151125152533.GC17308@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1053 Lines: 24 On Wed 25-11-15 16:25:33, Peter Zijlstra wrote: > On Wed, Nov 25, 2015 at 04:08:11PM +0100, Vlastimil Babka wrote: > > Now I admit I have no idea if there are architectures that don't support jump > > labels *and* have an expensive atomic read, and whether we care? > > atomic_read() is basically always READ_ONCE(), there's a few archs that > implement it in asm with a 'weird' load instruction, but its still a > load. The worst is I think an uncached load for blackfin or somesuch. > > There's plenty archs that do not support the jump label bits, but > typically you don't care much about those. I'm not aware of an arch that > cannot fundamentally implement jump_label support if they wanted to. OK, I see. Thanks for the clarification! Then I do not have any objections. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/