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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E4C5C433F5 for ; Wed, 10 Nov 2021 08:52:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A97E9611C0 for ; Wed, 10 Nov 2021 08:51:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A97E9611C0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 416BB6B006C; Wed, 10 Nov 2021 03:51:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3C6C96B0071; Wed, 10 Nov 2021 03:51:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B5B76B0072; Wed, 10 Nov 2021 03:51:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0217.hostedemail.com [216.40.44.217]) by kanga.kvack.org (Postfix) with ESMTP id 1CAF26B006C for ; Wed, 10 Nov 2021 03:51:59 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C227C184E6C64 for ; Wed, 10 Nov 2021 08:51:58 +0000 (UTC) X-FDA: 78792403116.07.39E9406 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by imf07.hostedemail.com (Postfix) with ESMTP id BBF7310004CB for ; Wed, 10 Nov 2021 08:51:57 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10163"; a="213358435" X-IronPort-AV: E=Sophos;i="5.87,223,1631602800"; d="scan'208";a="213358435" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Nov 2021 00:51:56 -0800 X-IronPort-AV: E=Sophos;i="5.87,223,1631602800"; d="scan'208";a="503882677" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.239.159.101]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Nov 2021 00:51:53 -0800 From: "Huang, Ying" To: Baolin Wang Cc: , , , , , , , , Subject: Re: [PATCH] mm: migrate: Support multiple target nodes demotion References: <8850612186ea23eb5d328d84e4008a6b60f418e1.1636514506.git.baolin.wang@linux.alibaba.com> Date: Wed, 10 Nov 2021 16:51:50 +0800 In-Reply-To: <8850612186ea23eb5d328d84e4008a6b60f418e1.1636514506.git.baolin.wang@linux.alibaba.com> (Baolin Wang's message of "Wed, 10 Nov 2021 15:03:36 +0800") Message-ID: <87ee7opf4p.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BBF7310004CB X-Stat-Signature: 19ccrjeqdihakqij9xapxjcn844psbfa Authentication-Results: imf07.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf07.hostedemail.com: domain of ying.huang@intel.com has no SPF policy when checking 192.55.52.151) smtp.mailfrom=ying.huang@intel.com X-HE-Tag: 1636534317-948485 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: Baolin Wang writes: > We have some machines with multiple memory types like below, which > have one fast (DRAM) memory node and two slow (persistent memory) memory > nodes. According to current node demotion, if node 0 fills up, ~~~~~~~~~~~~~ node demotion policy? > its memory should be migrated to node 1, when node 1 fills up, its > memory will be migrated to node 2: node 0 -> node 1 -> node 2 ->stop. > > But this is not efficient and suitbale memory migration route > for our machine with multiple slow memory nodes. Since the distance > between node 0 to node 1 and node 0 to node 2 is equal, and memory > migration between slow memory nodes will increase persistent memory > bandwidth greatly, which will hurt the whole system's performance. > > Thus for this case, we can treat the slow memory node 1 and node 2 > as a whole slow memory region, and we should migrate memory from > node 0 to node 1 and node 2 if node 0 fills up. > > This patch changes the node_demotion data structure to support multiple > target nodes, and establishes the migration path to support multiple > target nodes with validating if the node distance is the best or not. > > available: 3 nodes (0-2) > node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 > node 0 size: 62153 MB > node 0 free: 55135 MB > node 1 cpus: > node 1 size: 127007 MB > node 1 free: 126930 MB > node 2 cpus: > node 2 size: 126968 MB > node 2 free: 126878 MB > node distances: > node 0 1 2 > 0: 10 20 20 > 1: 20 10 20 > 2: 20 20 10 > > Signed-off-by: Baolin Wang > --- > Changes from RFC v2: > - Change to 'short' type for target nodes array. > - Remove nodemask instead selecting target node directly. > - Add WARN_ONCE() if the target nodes exceed the maximum value. > > Changes from RFC v1: > - Re-define the node_demotion structure. > - Set up multiple target nodes by validating the node distance. > - Add more comments. > --- > mm/migrate.c | 138 +++++++++++++++++++++++++++++++++++++++++++---------------- > 1 file changed, 102 insertions(+), 36 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index cf25b00..7f1d745 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -50,6 +50,7 @@ > #include > #include > #include > +#include > > #include > > @@ -1119,12 +1120,25 @@ static int __unmap_and_move(struct page *page, struct page *newpage, > * > * This is represented in the node_demotion[] like this: > * > - * { 1, // Node 0 migrates to 1 > - * 2, // Node 1 migrates to 2 > - * -1, // Node 2 does not migrate > - * 4, // Node 3 migrates to 4 > - * 5, // Node 4 migrates to 5 > - * -1} // Node 5 does not migrate > + * { nr=1, nodes[0]=1 }, // Node 0 migrates to 1 > + * { nr=1, nodes[0]=2 }, // Node 1 migrates to 2 > + * { nr=0, nodes[0]=-1 }, // Node 2 does not migrate > + * { nr=1, nodes[0]=4 }, // Node 3 migrates to 4 > + * { nr=1, nodes[0]=5 }, // Node 4 migrates to 5 > + * { nr=0, nodes[0]=-1} // Node 5 does not migrate > + * > + * Moreover some systems may have multiple same class memory > + * types. Suppose a system has one socket with 3 memory nodes, s/same class memory types/slow memory nodes/ ? We don't support multiple fast memory types, right? > + * node 0 is fast memory type, and node 1/2 both are slow memory > + * type, and the distance between fast memory node and slow > + * memory node is same. So the migration path should be: > + * > + * 0 -> 1/2 -> stop > + * > + * This is represented in the node_demotion[] like this: > + * { nr=2, {nodes[0]=1, nodes[1]=2} }, // Node 0 migrates to node 1 and node 2 > + * { nr=0, nodes[0]=-1, }, // Node 1 dose not migrate > + * { nr=0, nodes[0]=-1, }, // Node 2 does not migrate > */ > > /* > @@ -1135,8 +1149,13 @@ static int __unmap_and_move(struct page *page, struct page *newpage, > * must be held over all reads to ensure that no cycles are > * observed. > */ > -static int node_demotion[MAX_NUMNODES] __read_mostly = > - {[0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE}; > +#define DEMOTION_TARGET_NODES 15 > +struct demotion_nodes { > + unsigned short nr; > + short nodes[DEMOTION_TARGET_NODES]; > +}; > + > +static struct demotion_nodes node_demotion[MAX_NUMNODES] __read_mostly; If MAX_NUMNODES is 1024, the total size will be (16 * 2 * 1024) = 32K bytes. That appears too large. We may consider to allocate node_demotion[] dynamically. Best Regards, Huang, Ying