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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 BDCC7C11D24 for ; Fri, 21 Feb 2020 00:40:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7C120208CD for ; Fri, 21 Feb 2020 00:40:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Vuni54K9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C120208CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F29F76B0005; Thu, 20 Feb 2020 19:40:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EDB706B0006; Thu, 20 Feb 2020 19:40:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DC9FE6B0007; Thu, 20 Feb 2020 19:40:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0213.hostedemail.com [216.40.44.213]) by kanga.kvack.org (Postfix) with ESMTP id C2BB06B0005 for ; Thu, 20 Feb 2020 19:40:35 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 884A02495 for ; Fri, 21 Feb 2020 00:40:35 +0000 (UTC) X-FDA: 76512278430.21.flock92_5c6f7ed7fb119 X-HE-Tag: flock92_5c6f7ed7fb119 X-Filterd-Recvd-Size: 2797 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Fri, 21 Feb 2020 00:40:35 +0000 (UTC) Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C38E207FD; Fri, 21 Feb 2020 00:40:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582245634; bh=hZ3dGT7YJqIbKFGjdrNH8loYD4/AxKe4J06eOSLcC6E=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Vuni54K9568CmSjIYiNas2JBby91Xm/1JOEwM+Akreo8FEcnNdjw92J3r4Fgby+jT pk1so+82is8MWqD5UAYuxK8geIwlA1LW/FFWhOJ7lJ6iSyVYSX7n9NrgY9EQhl3s+p gULzSpzkWR1r5ADD8iZLWgU8yMj0xEGsqFnKxTfI= Date: Thu, 20 Feb 2020 16:40:33 -0800 From: Andrew Morton To: Joel Savitz Cc: linux-kernel@vger.kernel.org, Rafael Aquini , linux-mm@kvack.org Subject: Re: [PATCH] mm/page_alloc: increase default min_free_kbytes bound Message-Id: <20200220164033.8634c2c836c1558daebd81b9@linux-foundation.org> In-Reply-To: <20200220150103.5183-1-jsavitz@redhat.com> References: <20200220150103.5183-1-jsavitz@redhat.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 20 Feb 2020 10:01:03 -0500 Joel Savitz wrote: > > Currently, the vm.min_free_kbytes sysctl value is capped at a hardcoded > 64M in init_per_zone_wmark_min (unless it is overridden by khugepaged > initialization). > > This value has not been modified since 2005, and enterprise-grade > systems now frequently have hundreds of GB of RAM and multiple 10, 40, > or even 100 GB NICs. We have seen page allocation failures on heavily > loaded systems related to NIC drivers. These issues were resolved by an > increase to vm.min_free_kbytes. > > This patch increases the hardcoded value by a factor of 4 as a temporary > solution. OK, better than nothing I guess. > Further work to make the calculation of vm.min_free_kbytes more > consistent throughout the kernel would be desirable. > > As an example of the inconsistency of the current method, this value is > recalculated by init_per_zone_wmark_min() in the case of memory hotplug > which will override the value set by set_recommended_min_free_kbytes() > called during khugepaged initialization even if khugepaged remains > enabled, however an on/off toggle of khugepaged will then recalculate > and set the value via set_recommended_min_free_kbytes(). > Yup, these hardcoded numbers are lame.