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 71CE5C43611 for ; Wed, 31 Mar 2021 13:21:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47EE9619C1 for ; Wed, 31 Mar 2021 13:21:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235806AbhCaNV0 (ORCPT ); Wed, 31 Mar 2021 09:21:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:45802 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235314AbhCaNU4 (ORCPT ); Wed, 31 Mar 2021 09:20:56 -0400 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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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