From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 87C528E0001 for ; Wed, 19 Dec 2018 05:05:57 -0500 (EST) Received: by mail-ed1-f72.google.com with SMTP id d41so15608260eda.12 for ; Wed, 19 Dec 2018 02:05:57 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id l25si3319511edd.87.2018.12.19.02.05.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Dec 2018 02:05:56 -0800 (PST) Date: Wed, 19 Dec 2018 11:05:55 +0100 From: Michal Hocko Subject: Re: [PATCH v2] mm, page_isolation: remove drain_all_pages() in set_migratetype_isolate() Message-ID: <20181219100555.GD5758@dhcp22.suse.cz> References: <20181214023912.77474-1-richard.weiyang@gmail.com> <20181218204656.4297-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181218204656.4297-1-richard.weiyang@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Yang Cc: linux-mm@kvack.org, akpm@linux-foundation.org, osalvador@suse.de, david@redhat.com On Wed 19-12-18 04:46:56, Wei Yang wrote: [...] > Since drain_all_pages() is zone based, by reduce times of > drain_all_pages() also reduce some contention on this particular zone. I forgot to add. As said before this is a really weak justification. If there is really some contention then I would like to see some numbers backing that claim. A proper justification would be that reallying on draining in callers just sucks. As we can see we are doing that suboptimally based on a weak understanding of the functionality. So it makes sense to remove that draining and rely on the isolation code do the right thing. Then it is a clear cleanup. -- Michal Hocko SUSE Labs