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 77FF9C49EA5 for ; Fri, 25 Jun 2021 01:58:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EE39613BD for ; Fri, 25 Jun 2021 01:58:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233037AbhFYCBJ (ORCPT ); Thu, 24 Jun 2021 22:01:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58765 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232917AbhFYCBI (ORCPT ); Thu, 24 Jun 2021 22:01:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624586328; 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=L9xrjA2neFZYkOY/YN2ReKWB6xiN3ijuRxghJAKKGpI=; b=BdmNC4A+GQbVek05geBVCK7n8HIB7PQcvuDHxgHi9niboYCjqD/ZR/rQIYgwHnSe303BQI 6HoRQ6MfIrXxKMhvkJczU6PiJJmCWr1xKZMyiZHbGKS/+LOFbk5lgiiHVrWIPhF92OyjtO f9V+nEYBWaTADIrXjN09NQo3BCGTO0o= 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-435-XIyPpu8-PeK_5YA8FCE_Lg-1; Thu, 24 Jun 2021 21:58:44 -0400 X-MC-Unique: XIyPpu8-PeK_5YA8FCE_Lg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 11BD219057A5; Fri, 25 Jun 2021 01:58:43 +0000 (UTC) Received: from [10.64.54.70] (vpn2-54-70.bne.redhat.com [10.64.54.70]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BAB605D6AB; Fri, 25 Jun 2021 01:58:39 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH v4 3/4] mm/page_reporting: Allow driver to specify reporting order To: Alexander Duyck Cc: linux-mm , LKML , David Hildenbrand , "Michael S. Tsirkin" , Andrew Morton , Anshuman Khandual , Catalin Marinas , Will Deacon , shan.gavin@gmail.com References: <20210625014710.42954-1-gshan@redhat.com> <20210625014710.42954-4-gshan@redhat.com> From: Gavin Shan Message-ID: Date: Fri, 25 Jun 2021 14:00:09 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/25/21 11:19 AM, Alexander Duyck wrote: > On Thu, Jun 24, 2021 at 4:46 PM 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; >> + > > An alternative to this would be to look at setting up some > comparisons. I might add another variable and do something like: > order = prdev->order ? : pageblock_order; > if (order < page_reporting_order) > page_reporting_order = order; > > You could essentially do something similar in the previous patch but > just use pageblock_order directly rather than having to add a local > variable. > > That way if you need to still pull down the page reporting order you > can do so without prdev->order or pageblock_order overwriting the > value and pushing it back up. > Thanks, Alex. Lets do both in v5, which will be posted shortly. Thanks, Gavin