From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751636AbcIAGKW (ORCPT ); Thu, 1 Sep 2016 02:10:22 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:55070 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751139AbcIAGKW (ORCPT ); Thu, 1 Sep 2016 02:10:22 -0400 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: iamjoonsoo.kim@lge.com X-Original-SENDERIP: 10.177.222.138 X-Original-MAILFROM: iamjoonsoo.kim@lge.com Date: Thu, 1 Sep 2016 15:01:43 +0900 From: Joonsoo Kim To: "Aneesh Kumar K.V" Cc: Andrew Morton , Rik van Riel , Johannes Weiner , Mel Gorman , Laura Abbott , Minchan Kim , Marek Szyprowski , Michal Nazarewicz , Vlastimil Babka , Linux Memory Management List , LKML Subject: Re: [PATCH v5 0/6] Introduce ZONE_CMA Message-ID: <20160901060142.GA25364@js1304-P5Q-DELUXE> References: <1472447255-10584-1-git-send-email-iamjoonsoo.kim@lge.com> <8737lnudq6.fsf@linux.vnet.ibm.com> <87shtmsfpy.fsf@linux.vnet.ibm.com> <20160831080300.GB22757@js1304-P5Q-DELUXE> <87eg54rx1w.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87eg54rx1w.fsf@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 01, 2016 at 11:17:23AM +0530, Aneesh Kumar K.V wrote: > Joonsoo Kim writes: > > > On Tue, Aug 30, 2016 at 04:09:37PM +0530, Aneesh Kumar K.V wrote: > >> Joonsoo Kim writes: > >> > >> > 2016-08-29 18:27 GMT+09:00 Aneesh Kumar K.V : > >> >> js1304@gmail.com writes: > >> >> > >> >>> From: Joonsoo Kim > >> >>> > >> >>> Hello, > >> >>> > >> >>> Changes from v4 > >> >>> o Rebase on next-20160825 > >> >>> o Add general fix patch for lowmem reserve > >> >>> o Fix lowmem reserve ratio > >> >>> o Fix zone span optimizaion per Vlastimil > >> >>> o Fix pageset initialization > >> >>> o Change invocation timing on cma_init_reserved_areas() > >> >> > >> >> I don't see much information regarding how we interleave between > >> >> ZONE_CMA and other zones for movable allocation. Is that explained in > >> >> any of the patch ? The fair zone allocator got removed by > >> >> e6cbd7f2efb433d717af72aa8510a9db6f7a7e05 > >> > > >> > Interleaving would not work since the fair zone allocator policy is removed. > >> > I don't think that it's a big problem because it is just matter of > >> > timing to fill > >> > up the memory. Eventually, memory on ZONE_CMA will be fully used in > >> > any case. > >> > >> Does that mean a CMA allocation will now be slower because in most case we > >> will need to reclaim ? The zone list will now have ZONE_CMA in the > >> beginning right ? > > > > ZONE_CMA will be used first but I don't think that CMA allocation will > > be slower. In most case, memory would be fully used (usually > > by page cache). So, we need reclaim or migration in any case. > > Considering that the upstream kernel doesn't allow migration of THP > pages, this would mean that migrate will fail in most case if we have > THP enabled and the THP allocation request got satisfied via ZONE_CMA. > Isn't that going to be a problem ? I think that it is a separate problem. Once we restore utilization of CMA area, it would become a problem in any case. It is just hidden by utilization bug and should be handled separately. I guess that it's not that hard to fix that problem. Thanks.