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=-18.7 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=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 07116C4361A for ; Thu, 3 Dec 2020 16:15:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7BF48207A9 for ; Thu, 3 Dec 2020 16:15:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7BF48207A9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9E3596B0036; Thu, 3 Dec 2020 11:15:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9933B6B005C; Thu, 3 Dec 2020 11:15:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8A99D8D0001; Thu, 3 Dec 2020 11:15:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0088.hostedemail.com [216.40.44.88]) by kanga.kvack.org (Postfix) with ESMTP id 711796B0036 for ; Thu, 3 Dec 2020 11:15:11 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 20B853637 for ; Thu, 3 Dec 2020 16:15:11 +0000 (UTC) X-FDA: 77552470422.24.brain94_16080b1273bd Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id ECD391A4A0 for ; Thu, 3 Dec 2020 16:15:10 +0000 (UTC) X-HE-Tag: brain94_16080b1273bd X-Filterd-Recvd-Size: 3780 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Dec 2020 16:15:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607012109; h=from:from: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=MAA80sKrwAqbdNWVRk/U3s5sf/jojJUGYqWNq1RmsV0=; b=XYsyAgrFut4YTFdijy6yGJmcipufhc9KVh3fMwWGhnwAsx8d59vqmetChh7fBTgCKYgsZf 3wQJX0DYpkdcDySSULxBT6SbOvtfN4bxmke94a/g1csrC70iuEs1L//E7bnKDfVGzREcAa kqu8TvUXjg/6Fk3nOwEPKgjxTdOlBww= 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-396-JSp74mNdP06RwoHnK6VzGw-1; Thu, 03 Dec 2020 11:15:08 -0500 X-MC-Unique: JSp74mNdP06RwoHnK6VzGw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B3D7FBBEE3; Thu, 3 Dec 2020 16:15:06 +0000 (UTC) Received: from [10.36.113.250] (ovpn-113-250.ams2.redhat.com [10.36.113.250]) by smtp.corp.redhat.com (Postfix) with ESMTP id 07FC25D9CA; Thu, 3 Dec 2020 16:15:04 +0000 (UTC) Subject: Re: [PATCH 1/2] hv_balloon: simplify math in alloc_balloon_pages() To: Vitaly Kuznetsov , linux-hyperv@vger.kernel.org Cc: Wei Liu , Stephen Hemminger , Haiyang Zhang , Michael Kelley , Dexuan Cui , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20201202161245.2406143-1-vkuznets@redhat.com> <20201202161245.2406143-2-vkuznets@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <47b49c1a-6ea9-9b86-e08c-bb6915d79ea2@redhat.com> Date: Thu, 3 Dec 2020 17:15:04 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201202161245.2406143-2-vkuznets@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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: On 02.12.20 17:12, Vitaly Kuznetsov wrote: > 'alloc_unit' in alloc_balloon_pages() is either '512' for 2M allocations or > '1' for 4k allocations. So > > 1 << get_order(alloc_unit << PAGE_SHIFT) > > equals to 'alloc_unit' and the for loop basically sets all them offline. > Simplify the math to improve the readability. > > Signed-off-by: Vitaly Kuznetsov > --- > drivers/hv/hv_balloon.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c > index eb56e09ae15f..da3b6bd2367c 100644 > --- a/drivers/hv/hv_balloon.c > +++ b/drivers/hv/hv_balloon.c > @@ -1238,7 +1238,7 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm, > split_page(pg, get_order(alloc_unit << PAGE_SHIFT)); > > /* mark all pages offline */ > - for (j = 0; j < (1 << get_order(alloc_unit << PAGE_SHIFT)); j++) > + for (j = 0; j < alloc_unit; j++) > __SetPageOffline(pg + j); > > bl_resp->range_count++; > Right, alloc_unit is multiples of 4k pages, such that it can directly be used for page ranges in deflation/inflation paths. Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb