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=-0.7 required=3.0 tests=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 84014CA9EB5 for ; Mon, 4 Nov 2019 10:13:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 532A620578 for ; Mon, 4 Nov 2019 10:13:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 532A620578 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 029BD6B0006; Mon, 4 Nov 2019 05:13:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id F1C3F6B0007; Mon, 4 Nov 2019 05:13:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E59926B0008; Mon, 4 Nov 2019 05:13:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0070.hostedemail.com [216.40.44.70]) by kanga.kvack.org (Postfix) with ESMTP id CF68F6B0006 for ; Mon, 4 Nov 2019 05:13:26 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 5DA8B824999B for ; Mon, 4 Nov 2019 10:13:26 +0000 (UTC) X-FDA: 76118182812.07.order17_3af36bf83f61c X-HE-Tag: order17_3af36bf83f61c X-Filterd-Recvd-Size: 2801 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Mon, 4 Nov 2019 10:13:24 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Nov 2019 02:13:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,266,1569308400"; d="scan'208";a="401562144" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.29]) by fmsmga005.fm.intel.com with ESMTP; 04 Nov 2019 02:13:22 -0800 From: "Huang\, Ying" To: Peter Zijlstra Cc: , , 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 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> <20191104084404.GA4131@hirez.programming.kicks-ass.net> Date: Mon, 04 Nov 2019 18:13:21 +0800 In-Reply-To: <20191104084404.GA4131@hirez.programming.kicks-ass.net> (Peter Zijlstra's message of "Mon, 4 Nov 2019 09:44:04 +0100") Message-ID: <87bltsar0e.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Peter Zijlstra writes: > 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 :-) Thanks! Will do this in the next version. Best Regards, Huang, Ying