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=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 28FE2C49EA7 for ; Fri, 25 Jun 2021 06:04:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C5AA61414 for ; Fri, 25 Jun 2021 06:04:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233159AbhFYGHQ (ORCPT ); Fri, 25 Jun 2021 02:07:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:52315 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231923AbhFYGHO (ORCPT ); Fri, 25 Jun 2021 02:07:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624601093; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N1pzwVD62x/6KZDBAhY2ZWGnUYF4mbkQPcI7uLK8T28=; b=ftGMY7xrPaRrp6QW5tcKkfeMe8Q7/qvEgwCOOPejuREA8sM97ZpM3Ah1C4g18m/a2oULcC ggE3jrVevj0fKiH/n23jehGvxYYHMdOBbYFYQjspjwC3XpV3Y7V7iSoBpLzK4YQI5TVTZ6 v4AiUSxK3pRMfBPKWC7IpHUqxvMU8uk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-225-8y7uJH48NPiSN0NkmBP_tQ-1; Fri, 25 Jun 2021 02:04:52 -0400 X-MC-Unique: 8y7uJH48NPiSN0NkmBP_tQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A7998802C87; Fri, 25 Jun 2021 06:04:50 +0000 (UTC) Received: from [10.64.54.233] (vpn2-54-233.bne.redhat.com [10.64.54.233]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C800D19C44; Fri, 25 Jun 2021 06:04:40 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH v4 3/4] mm/page_reporting: Allow driver to specify reporting order To: "Michael S. Tsirkin" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, alexander.duyck@gmail.com, david@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, catalin.marinas@arm.com, will@kernel.org, shan.gavin@gmail.com References: <20210625014710.42954-1-gshan@redhat.com> <20210625014710.42954-4-gshan@redhat.com> <20210625014653-mutt-send-email-mst@kernel.org> From: Gavin Shan Message-ID: Date: Fri, 25 Jun 2021 16:04:38 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20210625014653-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/25/21 3:48 PM, Michael S. Tsirkin wrote: > On Fri, Jun 25, 2021 at 09:47:09AM +0800, Gavin Shan wrote: >> The page reporting order (threshold) is sticky to @pageblock_order >> by default. The page reporting can never be triggered because the >> freeing page can't come up with a free area like that huge. The >> situation becomes worse when the system memory becomes heavily >> fragmented. >> >> For example, the following configurations are used on ARM64 when 64KB >> base page size is enabled. In this specific case, the page reporting >> won't be triggered until the freeing page comes up with a 512MB free >> area. That's hard to be met, especially when the system memory becomes >> heavily fragmented. >> >> PAGE_SIZE: 64KB >> HPAGE_SIZE: 512MB >> pageblock_order: 13 (512MB) >> MAX_ORDER: 14 >> >> This allows the drivers to specify the page reporting order when the >> page reporting device is registered. It falls back to @pageblock_order >> if it's not specified by the driver. The existing users (hv_balloon >> and virtio_balloon) don't specify it and @pageblock_order is still >> taken as their page reporting order. So this shouldn't introduce any >> functional changes. >> >> Signed-off-by: Gavin Shan >> Reviewed-by: Alexander Duyck >> --- >> include/linux/page_reporting.h | 3 +++ >> mm/page_reporting.c | 6 ++++++ >> 2 files changed, 9 insertions(+) >> >> diff --git a/include/linux/page_reporting.h b/include/linux/page_reporting.h >> index 3b99e0ec24f2..fe648dfa3a7c 100644 >> --- a/include/linux/page_reporting.h >> +++ b/include/linux/page_reporting.h >> @@ -18,6 +18,9 @@ struct page_reporting_dev_info { >> >> /* Current state of page reporting */ >> atomic_t state; >> + >> + /* Minimal order of page reporting */ >> + unsigned int order; >> }; >> >> /* Tear-down and bring-up for page reporting devices */ >> diff --git a/mm/page_reporting.c b/mm/page_reporting.c >> index 34bf4d26c2c4..382958eef8a9 100644 >> --- a/mm/page_reporting.c >> +++ b/mm/page_reporting.c >> @@ -329,6 +329,12 @@ int page_reporting_register(struct page_reporting_dev_info *prdev) >> goto err_out; >> } >> >> + /* >> + * Update the page reporting order if it's specified by driver. >> + * Otherwise, it falls back to @pageblock_order. >> + */ >> + page_reporting_order = prdev->order ? : pageblock_order; >> + > > Hmm. So on ARM achitectures with 64K pages, the command line parameter > is silently ignored? > > Isn't this a problem? > It's fine as the command line parameter is used as debugging purpose. Besides, it can be changed by writing to the following file: /sys/module/page_reporting/parameters/page_reporting_order >> /* initialize state and work structures */ >> atomic_set(&prdev->state, PAGE_REPORTING_IDLE); >> INIT_DELAYED_WORK(&prdev->work, &page_reporting_process); >> -- >> 2.23.0 Thanks, Gavin