From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH] ARM: smp: Introduce ARCH_HAS_COMMON_CORES_CLOCK to speed-up boot Date: Thu, 20 Jan 2011 09:14:29 -0600 Message-ID: <4D385155.4050301@gmail.com> References: <1295516579-10225-1-git-send-email-santosh.shilimkar@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-yw0-f46.google.com ([209.85.213.46]:35218 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755795Ab1ATPOg (ORCPT ); Thu, 20 Jan 2011 10:14:36 -0500 Received: by ywl5 with SMTP id 5so194091ywl.19 for ; Thu, 20 Jan 2011 07:14:35 -0800 (PST) In-Reply-To: <1295516579-10225-1-git-send-email-santosh.shilimkar@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Santosh Shilimkar Cc: linux-arm-kernel@lists.infradead.org, Russell King , linux-omap@vger.kernel.org, Linus Walleij On 01/20/2011 03:42 AM, Santosh Shilimkar wrote: > On some architectures, secondary cores shares clock with primiary > core and hence scale together. Hence secondary core lpj calibration > is not necessary and can be skipped to save considerable time. > > This can speed up the secondary cpu boot and hotplug cpu online > paths. > > Discussion thread: > http://www.spinics.net/lists/arm-kernel/msg111124.html > There's already one way to do this with pre-calculated lpj. Also, this isn't multi-platform friendly. You could accomplish the same thing using the clock api to get the core frequency of each core and only calculate lpj if the frequency is different. Rob