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,URIBL_BLOCKED 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 62BC3C34056 for ; Wed, 19 Feb 2020 19:26:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2BB9F208E4 for ; Wed, 19 Feb 2020 19:26:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uuO8ONaw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BB9F208E4 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 C83816B0003; Wed, 19 Feb 2020 14:26:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C33D96B0006; Wed, 19 Feb 2020 14:26:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B49B76B0007; Wed, 19 Feb 2020 14:26:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0074.hostedemail.com [216.40.44.74]) by kanga.kvack.org (Postfix) with ESMTP id 9AF806B0003 for ; Wed, 19 Feb 2020 14:26:55 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4290B180AD811 for ; Wed, 19 Feb 2020 19:26:55 +0000 (UTC) X-FDA: 76507859190.10.sort94_3c5e668a78804 X-HE-Tag: sort94_3c5e668a78804 X-Filterd-Recvd-Size: 2018 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Wed, 19 Feb 2020 19:26:54 +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 09525208E4; Wed, 19 Feb 2020 19:26:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582140414; bh=Yc4u2FNt1IF2IbHtsIBwT/EjGq6IDcKxgr96tmofLT0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uuO8ONawyjT+YQsnSh9q7TNz5MXsxAChG8Jkavgb1IBkTn6/nlCiavADJp69yj4uH Q+hOztkuyRvzY7JZQcWs5x2xWSd9ckOLENn2Kme+eE4juIf23dHrA3g1XPIBd4Asjw WSHuBCjriM/qQ5bLTjugv90KBVY6t7QA5HNLpseA= Date: Wed, 19 Feb 2020 11:26:53 -0800 From: Andrew Morton To: Sultan Alsawaf Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: Stop kswapd early when nothing's waiting for it to free pages Message-Id: <20200219112653.116de9db314dade1f6086696@linux-foundation.org> In-Reply-To: <20200219182522.1960-1-sultan@kerneltoast.com> References: <20200219182522.1960-1-sultan@kerneltoast.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=0.040967, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 19 Feb 2020 10:25:22 -0800 Sultan Alsawaf wrote: > Keeping kswapd running when all the failed allocations that invoked it > are satisfied incurs a high overhead due to unnecessary page eviction > and writeback, as well as spurious VM pressure events to various > registered shrinkers. When kswapd doesn't need to work to make an > allocation succeed anymore, stop it prematurely to save resources. Seems sensible. Please fully describe the userspace-visible runtime effects of this change?