From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id BBA248E0038 for ; Thu, 10 Jan 2019 04:57:55 -0500 (EST) Received: by mail-ed1-f70.google.com with SMTP id b7so4170354eda.10 for ; Thu, 10 Jan 2019 01:57:55 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id hh8-v6si2588570ejb.41.2019.01.10.01.57.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jan 2019 01:57:54 -0800 (PST) Date: Thu, 10 Jan 2019 10:57:52 +0100 From: Michal Hocko Subject: Re: [PATCH RFC 0/3] mm: Reduce IO by improving algorithm of memcg pagecache pages eviction Message-ID: <20190110095752.GK31793@dhcp22.suse.cz> References: <154703479840.32690.6504699919905946726.stgit@localhost.localdomain> <20190109141113.GW31793@dhcp22.suse.cz> <20190109171021.GY31793@dhcp22.suse.cz> <3d4f4c83-44c9-c6d5-8dbe-c42a47e6c2bd@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3d4f4c83-44c9-c6d5-8dbe-c42a47e6c2bd@virtuozzo.com> Sender: owner-linux-mm@kvack.org List-ID: To: Kirill Tkhai Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, josef@toxicpanda.com, jack@suse.cz, hughd@google.com, darrick.wong@oracle.com, aryabinin@virtuozzo.com, guro@fb.com, mgorman@techsingularity.net, shakeelb@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu 10-01-19 12:42:02, Kirill Tkhai wrote: [...] > In general, I think a some time useful design is not a Bible, that nobody > is allowed to change. We should not limit us in something, in case of this > has a sense and may be useful. This is just a note in general. But any semantic exported to the userspace and real application depending on it is carved in stone for ever. And this is the case here I am afraid. So if we really need some sort of soft unmapping or reparenting a memory from a memcg then we really need to find a different way. I do not see a straightforward way right now TBH. -- Michal Hocko SUSE Labs