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=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 10AFDC4361A for ; Thu, 3 Dec 2020 16:16:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA995207A9 for ; Thu, 3 Dec 2020 16:16:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728720AbgLCQQk (ORCPT ); Thu, 3 Dec 2020 11:16:40 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:32792 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726032AbgLCQQi (ORCPT ); Thu, 3 Dec 2020 11:16:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607012111; 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=g8WAMFFF7MAf2nzZtvPMt6fqjCQWC/VJzpNgtLqg5Ns2uvt0Pj0DKf01ZJWxPZCbBPryIR 6a+kjeaMZ7oG6CcnDarWMrMGMkhskaY/iXeoW1vmiYgrw4if3KZcGH8gqNE1hrHmEu2qK2 i7lPuEGovZ8kQ7b36yp6TarUsLRG4qk= 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 Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org 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