From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756801AbcKXHnW (ORCPT ); Thu, 24 Nov 2016 02:43:22 -0500 Received: from outbound-smtp10.blacknight.com ([46.22.139.15]:35851 "EHLO outbound-smtp10.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752031AbcKXHnV (ORCPT ); Thu, 24 Nov 2016 02:43:21 -0500 Date: Thu, 24 Nov 2016 07:43:18 +0000 From: Mel Gorman To: Vlastimil Babka Cc: Linux-MM , Christoph Lameter , Michal Hocko , Johannes Weiner , Linux-Kernel Subject: Re: [RFC PATCH] mm: page_alloc: High-order per-cpu page allocator Message-ID: <20161124074318.a72wbn6lx5skxuxf@techsingularity.net> References: <20161121155540.5327-1-mgorman@techsingularity.net> <4a9cdec4-b514-e414-de86-fc99681889d8@suse.cz> <20161123163351.6s76ijwnqoakgcud@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: 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 Thu, Nov 24, 2016 at 08:26:39AM +0100, Vlastimil Babka wrote: > On 11/23/2016 05:33 PM, Mel Gorman wrote: > > > > + > > > > +static inline unsigned int pindex_to_order(unsigned int pindex) > > > > +{ > > > > + return pindex < MIGRATE_PCPTYPES ? 0 : pindex - MIGRATE_PCPTYPES + 1; > > > > +} > > > > + > > > > +static inline unsigned int order_to_pindex(int migratetype, unsigned int order) > > > > +{ > > > > + return (order == 0) ? migratetype : MIGRATE_PCPTYPES - 1 + order; > > > > > > Here I think that "MIGRATE_PCPTYPES + order - 1" would be easier to > > > understand as the array is for all migratetypes, but the order is shifted? > > > > > > > As in migratetypes * costly_order ? That would be excessively large. > > No, I just meant that instead of "MIGRATE_PCPTYPES - 1 + order" it could be > "MIGRATE_PCPTYPES + order - 1" as we are subtracting from order, not > migratetypes. Just made me confused a bit when seeing the code for the first > time. > Oh ok. At the time I was thinking in terms of the starting offset for the high-order and this seemed more natural but I'm ok with it either way. As an aside, the sizing of the array was still wrong but I corrected it yesterday shortly after sending the mail. I also realised that the free_pcppages_bulk was not interleaving properly and it should be fixed now. More tests are in progress. Thanks. -- Mel Gorman SUSE Labs