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 3F2848E0003 for ; Fri, 7 Dec 2018 05:32:03 -0500 (EST) Received: by mail-ed1-f71.google.com with SMTP id c18so1716419edt.23 for ; Fri, 07 Dec 2018 02:32:03 -0800 (PST) Date: Fri, 7 Dec 2018 11:32:00 +0100 From: Michal Hocko Subject: Re: [RFC Get rid of shrink code - memory-hotplug] Message-ID: <20181207103200.GV1286@dhcp22.suse.cz> References: <72455c1d4347d263cb73517187bc1394@suse.de> <39aa34058fc9641346456463afc2082d@suse.de> <20181205191244.GV1286@dhcp22.suse.cz> <42699b27-c214-91fd-e7e9-d34e16e9bf9f@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42699b27-c214-91fd-e7e9-d34e16e9bf9f@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: osalvador@suse.de, David Hildenbrand , dan.j.williams@gmail.com, pasha.tatashin@soleen.com, linux-mm@kvack.org, owner-linux-mm@kvack.org On Fri 07-12-18 10:54:50, Vlastimil Babka wrote: > 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. OK, this means that we have to carefully re-evaluate zone_contiguous for each offline operation. Thanks! -- Michal Hocko SUSE Labs