From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763356AbcLTMb1 (ORCPT ); Tue, 20 Dec 2016 07:31:27 -0500 Received: from outbound-smtp04.blacknight.com ([81.17.249.35]:59232 "EHLO outbound-smtp04.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757896AbcLTMbY (ORCPT ); Tue, 20 Dec 2016 07:31:24 -0500 Date: Tue, 20 Dec 2016 12:31:22 +0000 From: Mel Gorman To: Jia He Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Michal Hocko , Johannes Weiner , Joonsoo Kim , Taku Izumi Subject: Re: [PATCH RFC 1/1] mm, page_alloc: fix incorrect zone_statistics data Message-ID: <20161220123121.e4wgkxm2txdoxogo@techsingularity.net> References: <1481522347-20393-1-git-send-email-hejianet@gmail.com> <1481522347-20393-2-git-send-email-hejianet@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1481522347-20393-2-git-send-email-hejianet@gmail.com> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 12, 2016 at 01:59:07PM +0800, Jia He wrote: > In commit b9f00e147f27 ("mm, page_alloc: reduce branches in > zone_statistics"), it reconstructed codes to reduce the branch miss rate. > Compared with the original logic, it assumed if !(flag & __GFP_OTHER_NODE) > z->node would not be equal to preferred_zone->node. That seems to be > incorrect. > > Fixes: commit b9f00e147f27 ("mm, page_alloc: reduce branches in > zone_statistics") > > Signed-off-by: Jia He This is slightly curious. It appear it would only occur if a process was running on a node that was outside the memory policy. Can you confirm that is the case? If so, your patch is a a semantic curiousity because it's actually impossible for a NUMA allocation to be local and the definition of "HIT" is fuzzy enough to be useless. I won't object to the patch but it makes me trust "hit" even less than I already do for any analysis. Note that after this mail that I'll be unavailable by mail until early new years. -- Mel Gorman SUSE Labs