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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 D587CC2BB55 for ; Wed, 15 Apr 2020 11:33:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B273220737 for ; Wed, 15 Apr 2020 11:33:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Hvd2px1g" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393937AbgDOLdA (ORCPT ); Wed, 15 Apr 2020 07:33:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390657AbgDOLcn (ORCPT ); Wed, 15 Apr 2020 07:32:43 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF565C061A0C for ; Wed, 15 Apr 2020 04:32:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=IJiQ+eOHsfyCYt3l0kllphhznQD2NCgBQ/HSamSBJWY=; b=Hvd2px1ghMgtRjoeyAfhjQ4Pgg wF35jYsZarX+C95QKpbHD2KQpRe+JDpJIuuu7Sgw6wyCMWobQVpi8CgvB4XND6weM357HTLruYWJA yq/rBe56qZQDyyxhVR2SB0NPKPTuUDZ4FWaYVuB6DSv98kdM9tpI3tJnljUuR8JvSfZIRKKxOL7qy f+9Wy1/y8jaYpNmju0yyfO9ZBY0RtnVtWz1cqM+vi+br0lCAt3eHoUiLcYstMed0HkSFqBJ8kqeOi GagxHZAMETWaDiG7TvDzCmQOr8P77GRvHU4p4JFXmAVvjmK4+iAIolj4oGQQmQYIH9jtOuK6XwnpQ DzqviHUA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jOgHN-000539-M3; Wed, 15 Apr 2020 11:32:29 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0CA7F30066E; Wed, 15 Apr 2020 13:32:26 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C2365203A8983; Wed, 15 Apr 2020 13:32:26 +0200 (CEST) Date: Wed, 15 Apr 2020 13:32:26 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Huang Ying , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ingo Molnar , Mel Gorman , Rik van Riel , Daniel Jordan , Tejun Heo , Dave Hansen , Tim Chen , Aubrey Li Subject: Re: [RFC] autonuma: Support to scan page table asynchronously Message-ID: <20200415113226.GE20730@hirez.programming.kicks-ass.net> References: <20200414081951.297676-1-ying.huang@intel.com> <20200414120646.GN3818@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200414120646.GN3818@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 14, 2020 at 01:06:46PM +0100, Mel Gorman wrote: > While it's just an opinion, my preference would be to focus on reducing > the cost and amount of scanning done -- particularly for threads. This; I really don't believe in those back-charging things, esp. since not having cgroups or having multiple applications in a single cgroup is a valid setup. Another way to reduce latency spikes is to decrease both sysctl_numa_balancing_scan_delay and sysctl_numa_balancing_scan_size. Then you do more smaller scans. By scanning more often you reduce the contrast, by reducing the size you lower the max latency. And this is all assuming you actually want numa balancing for this process.