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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B398EC433EF for ; Thu, 28 Oct 2021 14:37:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 269FC60F9C for ; Thu, 28 Oct 2021 14:37:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 269FC60F9C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id A576E6B006C; Thu, 28 Oct 2021 10:37:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A06CE6B0071; Thu, 28 Oct 2021 10:37:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8A78C940007; Thu, 28 Oct 2021 10:37:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0236.hostedemail.com [216.40.44.236]) by kanga.kvack.org (Postfix) with ESMTP id 6119F6B006C for ; Thu, 28 Oct 2021 10:37:53 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E6842181C4434 for ; Thu, 28 Oct 2021 14:37:52 +0000 (UTC) X-FDA: 78746100384.13.7CE974A Received: from outbound-smtp35.blacknight.com (outbound-smtp35.blacknight.com [46.22.139.218]) by imf22.hostedemail.com (Postfix) with ESMTP id 2D17B191D for ; Thu, 28 Oct 2021 14:37:52 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp35.blacknight.com (Postfix) with ESMTPS id 7E5D61B8D for ; Thu, 28 Oct 2021 15:37:50 +0100 (IST) Received: (qmail 28947 invoked from network); 28 Oct 2021 14:37:50 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.29]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 28 Oct 2021 14:37:50 -0000 Date: Thu, 28 Oct 2021 15:37:48 +0100 From: Mel Gorman To: Sebastian Andrzej Siewior Cc: Andrew Morton , linux-mm@kvack.org, Vlastimil Babka , Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH] mm: Disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT Message-ID: <20211028143748.GU3959@techsingularity.net> References: <20211028143327.hfbxjze7palrpfgp@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20211028143327.hfbxjze7palrpfgp@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 2D17B191D X-Stat-Signature: wa93tc4bumryd5pjh1dgo5hsxsbct9pw Authentication-Results: imf22.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf22.hostedemail.com: domain of mgorman@techsingularity.net designates 46.22.139.218 as permitted sender) smtp.mailfrom=mgorman@techsingularity.net X-HE-Tag: 1635431872-743955 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Oct 28, 2021 at 04:33:27PM +0200, Sebastian Andrzej Siewior wrote: > TRANSPARENT_HUGEPAGE: > There are potential non-deterministic delays to an RT thread if a critical > memory region is not THP-aligned and a non-RT buffer is located in the same > hugepage-aligned region. It's also possible for an unrelated thread to migrate > pages belonging to an RT task incurring unexpected page faults due to memory > defragmentation even if khugepaged is disabled. > > Regular HUGEPAGEs are not affected by this can be used. > > NUMA_BALANCING: > There is a non-deterministic delay to mark PTEs PROT_NONE to gather NUMA fault > samples, increased page faults of regions even if mlocked and non-deterministic > delays when migrating pages. > > [Mel Gorman worded 99% of the commit description]. > > Link: https://lore.kernel.org/all/20200304091159.GN3818@techsingularity.net/ > Link: https://lore.kernel.org/all/20211026165100.ahz5bkx44lrrw5pt@linutronix.de/ > Cc: Mel Gorman > Signed-off-by: Sebastian Andrzej Siewior Acked-by: Mel Gorman -- Mel Gorman SUSE Labs