From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 838E5C433B4 for ; Wed, 31 Mar 2021 13:20:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2681861968 for ; Wed, 31 Mar 2021 13:20:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2681861968 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8F3DE6B007D; Wed, 31 Mar 2021 09:20:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A4BB6B0081; Wed, 31 Mar 2021 09:20:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 743A36B0082; Wed, 31 Mar 2021 09:20:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0096.hostedemail.com [216.40.44.96]) by kanga.kvack.org (Postfix) with ESMTP id 57CFD6B007D for ; Wed, 31 Mar 2021 09:20:57 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0FF9F364A for ; Wed, 31 Mar 2021 13:20:57 +0000 (UTC) X-FDA: 77980229754.16.808857A Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf19.hostedemail.com (Postfix) with ESMTP id C4A9F90009E2 for ; Wed, 31 Mar 2021 13:20:55 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 93AA6B21D; Wed, 31 Mar 2021 13:20:55 +0000 (UTC) Date: Wed, 31 Mar 2021 14:20:53 +0100 From: Mel Gorman To: Gerald Schaefer Cc: Yang Shi , kirill.shutemov@linux.intel.com, ziy@nvidia.com, mhocko@suse.com, ying.huang@intel.com, hughd@google.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Alexander Gordeev Subject: Re: [RFC PATCH 0/6] mm: thp: use generic THP migration for NUMA hinting fault Message-ID: <20210331132053.GW15768@suse.de> References: <20210329183312.178266-1-shy828301@gmail.com> <20210330164200.01a4b78f@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20210330164200.01a4b78f@thinkpad> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: C4A9F90009E2 X-Stat-Signature: 7da4twnxex3zwjy6gpotcsdwcnmwfn4i X-Rspamd-Server: rspam02 Received-SPF: none (suse.de>: No applicable sender policy available) receiver=imf19; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: none/none X-HE-Tag: 1617196855-291413 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000822, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 30, 2021 at 04:42:00PM +0200, Gerald Schaefer wrote: > Could there be a work-around by splitting THP pages instead of marking them > as migrate pmds (via pte swap entries), at least when THP migration is not > supported? I guess it could also be acceptable if THP pages were simply not > migrated for NUMA balancing on s390, but then we might need some extra config > option to make that behavior explicit. > The split is not done on other architectures simply because the loss from splitting exceeded the gain of improved locality in too many cases. However, it might be ok as an s390-specific workaround. (Note, I haven't read the rest of the series due to lack of time but this query caught my eye). -- Mel Gorman SUSE Labs