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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 65187C35671 for ; Mon, 24 Feb 2020 12:03:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2EBD820828 for ; Mon, 24 Feb 2020 12:03:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="g1I9RIlP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727429AbgBXMDO (ORCPT ); Mon, 24 Feb 2020 07:03:14 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:39532 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727265AbgBXMDN (ORCPT ); Mon, 24 Feb 2020 07:03:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=t5KPllfCzU4AasIlRCx7IzfWUIVfM/xDWS4+N7wn5YA=; b=g1I9RIlPEPLzZWdOSbIZxCjpj LpMV7CqOwjfFjrIcnMazJf2/Mmg90x8pv9//qmp8jQeSXfZjcEgb41hEb0Cpa+JHdndB/RDrHMXEl kWz02pgsYVHwIV4OEGIvsFv7Zm5QioaBlb2MUhpFH7eu7fQoVzymGUxZZ0fMCIkyqDk1cT36KuBGE iO73eFzbLIc6kluM0d8NpnNsm0iSbUFe1j3WLJFgVwOe69LzYFiPwTvkfQdqP98jFOyoqtFohXZQJ NGcvXqREeIXSER4KikTrW7pnujpKNi56cCH2F1FGoJqfsDl2o/y/N349pCffazDf2+vgVaH715U5T EkbTycHjg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:56262) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1j6CS5-0002Xr-Ky; Mon, 24 Feb 2020 12:03:09 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1j6CRz-0006P7-9v; Mon, 24 Feb 2020 12:03:03 +0000 Date: Mon, 24 Feb 2020 12:03:03 +0000 From: Russell King - ARM Linux admin To: yifeng wu Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: Subject: [PATCH] arm/kernel/head.S: optimize __create_page_tables function Message-ID: <20200224120303.GQ25745@shell.armlinux.org.uk> References: <20200224110508.GP25745@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Mon, Feb 24, 2020 at 07:54:07PM +0800, yifeng wu wrote: > Thank you very much for your reply. > I have tested on my machine. It takes about 0.5 seconds to copy the memory > (16M size) with "str" instruction, and only 0.1 seconds with "stmia" ITYM 16k. You say "copy" but we're setting memory to zero. I'm quite surprised by that difference, which CPU was this measured on? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up