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 933FCC18E00 for ; Wed, 19 Feb 2020 19:27:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A5B124671 for ; Wed, 19 Feb 2020 19:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582140420; bh=Yc4u2FNt1IF2IbHtsIBwT/EjGq6IDcKxgr96tmofLT0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=IDqCFIJHoYWs+UEfsEs6CVrEuh8RnwZmE45d0RVmzPiBie0GzPCZft1MltyTtp3iO e4M3WPX0P9xup81xjM5gaGCSkTZaew6RbR+5PUmAxkaptmRokT8dg8T0n2tWx7oFcN F731hN773v+EfAkC/2tDkEToMAZar/7GPuuXG6ZI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726891AbgBST0y (ORCPT ); Wed, 19 Feb 2020 14:26:54 -0500 Received: from mail.kernel.org ([198.145.29.99]:46558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726719AbgBST0y (ORCPT ); Wed, 19 Feb 2020 14:26:54 -0500 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?