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=-12.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 0559CC433DF for ; Mon, 3 Aug 2020 13:29:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D06B7206DA for ; Mon, 3 Aug 2020 13:29:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="xdhDCEB5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726825AbgHCN3I (ORCPT ); Mon, 3 Aug 2020 09:29:08 -0400 Received: from mail29.static.mailgun.info ([104.130.122.29]:31336 "EHLO mail29.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726398AbgHCN3I (ORCPT ); Mon, 3 Aug 2020 09:29:08 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1596461347; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=5lz/yjuFSbfi7AP16DemqYxIyN/7sfSVueFdw1yEZKU=; b=xdhDCEB56/5qVQt4nvInLbSFbXofGuzl2oi5fGyrRygDOqHSLFzgvELjCO586xbD6lwHUJNd NwEDxVVN5Dk0w6qWJ7h5isRk9BPolWIfivZPcUrJleEM57TMHGov2zZeTJvO8bbjLEfSGCq7 H9NprDY5bNozGc5DzXvwfLsDtXQ= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n07.prod.us-west-2.postgun.com with SMTP id 5f28110f21feae908b7919f3 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Mon, 03 Aug 2020 13:28:47 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 5A305C43395; Mon, 3 Aug 2020 13:28:46 +0000 (UTC) Received: from [192.168.1.103] (unknown [183.83.143.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: charante) by smtp.codeaurora.org (Postfix) with ESMTPSA id 1E264C433C9; Mon, 3 Aug 2020 13:28:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 1E264C433C9 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=charante@codeaurora.org Subject: Re: [PATCH] mm, memory_hotplug: update pcp lists everytime onlining a memory block To: David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, vinmenon@codeaurora.org References: <1596372896-15336-1-git-send-email-charante@codeaurora.org> From: Charan Teja Kalla Message-ID: Date: Mon, 3 Aug 2020 18:58:42 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks David for the comments. On 8/3/2020 1:35 PM, David Hildenbrand wrote: > On 02.08.20 14:54, Charan Teja Reddy wrote: >> When onlining a first memory block in a zone, pcp lists are not updated >> thus pcp struct will have the default setting of ->high = 0,->batch = 1. >> This means till the second memory block in a zone(if it have) is onlined >> the pcp lists of this zone will not contain any pages because pcp's >> ->count is always greater than ->high thus free_pcppages_bulk() is >> called to free batch size(=1) pages every time system wants to add a >> page to the pcp list through free_unref_page(). To put this in a word, >> system is not using benefits offered by the pcp lists when there is a >> single onlineable memory block in a zone. Correct this by always >> updating the pcp lists when memory block is onlined. > > I guess such setups are rare ... but I can imagine it being the case > with virtio-mem in the future ... not 100% if this performance > optimization is really relevant in practice ... how did you identify this? Even the Snapdragon hardware that I had tested on contain multiple onlineable memory blocks. But we have the use case in which we online single memory block and once it is filled then online the next block. In the step where single block is onlined, we observed the below pageset params. pagesets cpu: 0 count: 0 high: 0 batch: 1 Once the second block is onlined then only seeing some sane values as below. cpu: 0 count: 32 high: 378 batch: 63 In the above case, till the second block is onlined, no page is held in the pcp list. So, updating the pcp params every time when onlining the memory block is required, as an example in the usecase that I had mentioned. > >> >> Signed-off-by: Charan Teja Reddy >> --- >> mm/memory_hotplug.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index dcdf327..7f62d69 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -854,8 +854,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, >> node_states_set_node(nid, &arg); >> if (need_zonelists_rebuild) >> build_all_zonelists(NULL); >> - else >> - zone_pcp_update(zone); >> + zone_pcp_update(zone); >> >> init_per_zone_wmark_min(); >> >> > > Does, in general, look sane to me. > > Reviewed-by: David Hildenbrand Thanks for the ACK. > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project