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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 9058BCA9ECF for ; Mon, 4 Nov 2019 08:44:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6478B222CA for ; Mon, 4 Nov 2019 08:44:15 +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="QT+iriO4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727907AbfKDIoO (ORCPT ); Mon, 4 Nov 2019 03:44:14 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:56746 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727553AbfKDIoN (ORCPT ); Mon, 4 Nov 2019 03:44:13 -0500 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=lnIuRdr4CYsrlQgJxc+GH9Enm/uWxg114yr6D6OF8ic=; b=QT+iriO4E/1wFUY4RwRYBB4Tw OdaMGxiHmM2NCSCiewk4iESvBle369Lj7ru7q69JoMWgR32C8a3bmeHxx49KVYKFKzqOeF3G0b4N/ G+OYnywEroYsP69gMOd/n0+iVc0X57r0P9NGjFomM6WUgjYxzbX3jly/93JjmvyEGsM56NYLQQaHx 0bCrCZCbDXVH41Rhn12ISQEwYsCjI9K+hAyXjkGmgkvPtIPh9imMdfkXUYSDthrwoIpAXsVeK0ZKK uV5nZpdRPE6/bDcDlGDIDYc5y2AYC6KPcZ6YQpHKz25rDLk2pOJv6V1hIiMfY2tOGPCkMwNyGgFiW mIBNQiQhQ==; 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 1iRXy3-0000nv-16; Mon, 04 Nov 2019 08:44:07 +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 B0C0C305EF2; Mon, 4 Nov 2019 09:43:01 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D9AEC23CEFEAF; Mon, 4 Nov 2019 09:44:04 +0100 (CET) Date: Mon, 4 Nov 2019 09:44:04 +0100 From: Peter Zijlstra To: "Huang, Ying" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Michal Hocko , Rik van Riel , Mel Gorman , Ingo Molnar , Dave Hansen , Dan Williams , Fengguang Wu Subject: Re: [RFC 08/10] autonuma, memory tiering: Select hotter pages to promote to fast memory node Message-ID: <20191104084404.GA4131@hirez.programming.kicks-ass.net> References: <20191101075727.26683-1-ying.huang@intel.com> <20191101075727.26683-9-ying.huang@intel.com> <20191101092404.GS4131@hirez.programming.kicks-ass.net> <87k18gcqih.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k18gcqih.fsf@yhuang-dev.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 04, 2019 at 10:41:10AM +0800, Huang, Ying wrote: > >> +#define NUMA_SCAN_NR_HIST 16 > >> + int numa_scan_idx; > >> + unsigned long numa_scan_jiffies[NUMA_SCAN_NR_HIST]; > >> + unsigned long numa_scan_starts[NUMA_SCAN_NR_HIST]; > > > > Why 16? This is 4 cachelines. > > We want to keep the NUMA scanning history reasonably long. From > task_scan_min(), the minimal interval between task_numa_work() running > is about 100 ms by default. So we can keep 1600 ms history by default > if NUMA_SCAN_NR_HIST is 16. If user choose to use smaller > sysctl_numa_balancing_scan_size, then we can only keep shorter history. > In general, we want to keep no less than 1000 ms history. So 16 appears > like a reasonable choice for us. Any other suggestion? This is very good information for Changelogs and comments :-)