From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id DAD296B7FEF for ; Fri, 7 Dec 2018 04:54:52 -0500 (EST) Received: by mail-ed1-f71.google.com with SMTP id c34so1685419edb.8 for ; Fri, 07 Dec 2018 01:54:52 -0800 (PST) Subject: Re: [RFC Get rid of shrink code - memory-hotplug] References: <72455c1d4347d263cb73517187bc1394@suse.de> <39aa34058fc9641346456463afc2082d@suse.de> <20181205191244.GV1286@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <42699b27-c214-91fd-e7e9-d34e16e9bf9f@suse.cz> Date: Fri, 7 Dec 2018 10:54:50 +0100 MIME-Version: 1.0 In-Reply-To: <20181205191244.GV1286@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , osalvador@suse.de Cc: David Hildenbrand , dan.j.williams@gmail.com, pasha.tatashin@soleen.com, linux-mm@kvack.org, owner-linux-mm@kvack.org On 12/5/18 8:12 PM, Michal Hocko wrote: > [Cc Vlastimil] > > On Tue 04-12-18 13:43:31, osalvador@suse.de wrote: >> On 2018-12-04 12:31, David Hildenbrand wrote: >> > If I am not wrong, zone_contiguous is a pure mean for performance >>> improvement, right? So leaving zone_contiguous unset is always save. I >>> always disliked the whole clear/set_zone_contiguous thingy. I wonder if >>> we can find a different way to boost performance there (in the general >>> case). Or is this (zone_contiguous) even worth keeping around at all for >>> now? (do we have performance numbers?) >> >> It looks like it was introduced by 7cf91a98e607 >> ("mm/compaction: speed up pageblock_pfn_to_page() when zone is contiguous"). >> >> The improve numbers are in the commit. >> So I would say that we need to keep it around. > > Is that still the case though? Well, __pageblock_pfn_to_page() has to be called for each pageblock in compaction, when zone_contiguous is false. And that's unchanged since the introduction of zone_contiguous, so the numbers should still hold.