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=0.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,URIBL_DBL_ABUSE_MALW,USER_AGENT_SANE_1 autolearn=no 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 C77C5C35254 for ; Wed, 5 Feb 2020 12:53:08 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 96BA420702 for ; Wed, 5 Feb 2020 12:53:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="IPXmqGLn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 96BA420702 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Mime-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=TrW2Defyz6ld/KtpE9qChUDod/w5h2C8f+9NI7tKlT0=; b=IPXmqGLnzn+ISu qS+Cjtit5rXuvEY+qm0sQ6vAmGqfJGWfy4KYgDBgaRD6Ej2stwGi91jgKIoX5ToK3qKoLEWcXSdLi G3xIBr42JB4y52PtjsyYX2/aiUgBw6+7Wm0wFhKfC1FqzeYWR4cHYB1teQhsbP6YtKNlzBS4i+qB8 0j8wB07v+dN/n8MFspzeCT6sJfsf+CKpmsrhRY56Nsw2D5Q4/Df0gVGUcPjkKl1Acka6s6tAzQRjf NJEC2rMfAVoQVs41kROHf1jfvGpJGUI3sH/f+gvNKzwNOahEMM+616gTd1+Zwkf6dysnzTL8JGl1J K7A3X7zzYVQXSmqoUi3A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1izKB0-0003t3-PR; Wed, 05 Feb 2020 12:53:06 +0000 Received: from gate.crashing.org ([63.228.1.57]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1izKAx-0003s7-T8 for linux-arm-kernel@lists.infradead.org; Wed, 05 Feb 2020 12:53:05 +0000 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 015CppFf030570; Wed, 5 Feb 2020 06:51:51 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 015Cpn3x030569; Wed, 5 Feb 2020 06:51:49 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Wed, 5 Feb 2020 06:51:49 -0600 From: Segher Boessenkool To: David Hildenbrand Subject: Re: [PATCH v6 10/10] mm/memory_hotplug: Cleanup __remove_pages() Message-ID: <20200205125149.GS22482@gate.crashing.org> References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-11-david@redhat.com> <20200204094652.GE6494@linux> <5d698f94-af18-0714-bc97-14b6c520572c@redhat.com> <20200204131353.GJ22482@gate.crashing.org> <0e2f700c-b01b-8c16-99c2-2648967fc203@redhat.com> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: <0e2f700c-b01b-8c16-99c2-2648967fc203@redhat.com> User-Agent: Mutt/1.4.2.3i X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200205_045304_087686_980A0A2A X-CRM114-Status: GOOD ( 15.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, Michal Hocko , linux-ia64@vger.kernel.org, Pavel Tatashin , linux-sh@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Wei Yang , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Feb 04, 2020 at 02:38:51PM +0100, David Hildenbrand wrote: > On 04.02.20 14:13, Segher Boessenkool wrote: > > On Tue, Feb 04, 2020 at 01:41:06PM +0100, David Hildenbrand wrote: > >> It's a pattern commonly used in compilers and emulators to calculate the > >> number of bytes to the next block/alignment. (we're missing a macro > >> (like we have ALIGN_UP/IS_ALIGNED) for that - but it's hard to come up > >> with a good name (e.g., SIZE_TO_NEXT_ALIGN) . > > You can just write the easy to understand > > > > ... ALIGN_UP(x) - x ... > > you mean > > ALIGN_UP(x, PAGES_PER_SECTION) - x > > but ... > > > which is better *without* having a separate name. Does that not > > generate good machine code for you? > > 1. There is no ALIGN_UP. "SECTION_ALIGN_UP(x) - x" would be possible Erm, you started it ;-) > 2. It would be wrong if x is already aligned. > > e.g., let's use 4096 for simplicity as we all know that value by heart > (for both x and the block size). > > a) -(4096 | -4096) -> 4096 > > b) #define ALIGN_UP(x, a) ((x + a - 1) & -(a)) > > ALIGN_UP(4096, 4096) - 4096 -> 0 > > Not as easy as it seems ... If you always want to return a number >= 1, it it simply ALIGN_UP(x + 1) - x (and replace 1 by any other minimum size required). This *also* is easy to read, without having to have any details (and quirks :-/ ) of those utility functions memorised. Segher _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel