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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 A78E6C352BE for ; Fri, 17 Apr 2020 12:45:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 859942083E for ; Fri, 17 Apr 2020 12:45:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="mWXaRH/e" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729770AbgDQMpa (ORCPT ); Fri, 17 Apr 2020 08:45:30 -0400 Received: from smtp-fw-6002.amazon.com ([52.95.49.90]:44288 "EHLO smtp-fw-6002.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729176AbgDQMp3 (ORCPT ); Fri, 17 Apr 2020 08:45:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1587127529; x=1618663529; h=from:to:cc:subject:date:message-id:in-reply-to: mime-version; bh=VxdcW703gWBgz7FjjmMl11fS0NzvwPPH68Vk83e+i3s=; b=mWXaRH/eX9vv2t/jT0tgayZlg0oHUY+JDkHZR3iLPz/TIbVkX78wbcES yAM4lsBxid8TLNSewdyNthgQFIaXYmraA4+XR+znNnRrccecgvyxL0xdg Sb/xTw0mVTvCiGHMrjHHi5AnpDKXb+PFQA4RP09IMibJnZ7zZto5GQRXQ E=; IronPort-SDR: Uwjivzvoj5wIrsPJMQnmh8OIZG1IMiibxXi2pVfuBwu3II9eAc8zOYplTvCSBdMmURrkrxR6xO uk7l3VpanCRw== X-IronPort-AV: E=Sophos;i="5.72,395,1580774400"; d="scan'208";a="25954007" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-1a-7d76a15f.us-east-1.amazon.com) ([10.43.8.6]) by smtp-border-fw-out-6002.iad6.amazon.com with ESMTP; 17 Apr 2020 12:45:16 +0000 Received: from EX13MTAUEA002.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan2.iad.amazon.com [10.40.159.162]) by email-inbound-relay-1a-7d76a15f.us-east-1.amazon.com (Postfix) with ESMTPS id 2A0FFA236A; Fri, 17 Apr 2020 12:45:15 +0000 (UTC) Received: from EX13D31EUA001.ant.amazon.com (10.43.165.15) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 17 Apr 2020 12:45:14 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.162.238) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 17 Apr 2020 12:45:03 +0000 From: SeongJae Park To: Mel Gorman CC: SeongJae Park , Peter Zijlstra , "Huang, Ying" , , , Ingo Molnar , Mel Gorman , Rik van Riel , Daniel Jordan , Tejun Heo , Dave Hansen , Tim Chen , Aubrey Li Subject: Re: Re: Re: Re: [RFC] autonuma: Support to scan page table asynchronously Date: Fri, 17 Apr 2020 14:44:37 +0200 Message-ID: <20200417124437.25445-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200417121629.GA3758@techsingularity.net> (raw) MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.162.238] X-ClientProxiedBy: EX13D06UWA004.ant.amazon.com (10.43.160.164) To EX13D31EUA001.ant.amazon.com (10.43.165.15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 17 Apr 2020 13:16:29 +0100 Mel Gorman wrote: > On Fri, Apr 17, 2020 at 12:21:29PM +0200, SeongJae Park wrote: > > On Fri, 17 Apr 2020 12:04:17 +0200 Peter Zijlstra wrote: > > > > > On Fri, Apr 17, 2020 at 09:05:08AM +0200, SeongJae Park wrote: > > > > I think the main idea of DAMON[1] might be able to applied here. Have you > > > > considered it? > > > > > > > > [1] https://lore.kernel.org/linux-mm/20200406130938.14066-1-sjpark@amazon.com/ > > > > > > I've ignored that entire thing after you said the information it > > > provides was already available through the PMU. > > > > Sorry if my answer made you confused. What I wanted to say was that the > > fundamental access checking mechanism that DAMON depends on is PTE Accessed bit > > for now, but it could be modified to use PMU or other features instead. > > I would not be inclined to lean towards either approach for NUMA > balancing. Fiddling with the accessed bit can have consequences for page > aging and residency -- fine for debugging a problem, not to fine for > normal usage. I would expect the PMU approach would have high overhead > as well as taking over a PMU counter that userspace debugging may expect > to be available. Good point. But, isn't it ok to use Accessed bit as long as PG_Idle and PG_Young is adjusted properly? Current DAMON implementation does so, as idle_page_tracking also does. That said, the core logics of DAMON and the underlying access check primitive are logically seperated. I am planning[1] to further entirely seperate those and let users to be able to use right access check promitive for their needs. If I'm missing something, please let me know. [1] https://lore.kernel.org/linux-mm/20200409094232.29680-1-sjpark@amazon.com/ Thanks, SeongJae Park > > -- > Mel Gorman > SUSE Labs