From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755621Ab3J1GIQ (ORCPT ); Mon, 28 Oct 2013 02:08:16 -0400 Received: from mail-ie0-f180.google.com ([209.85.223.180]:53859 "EHLO mail-ie0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755563Ab3J1GIO (ORCPT ); Mon, 28 Oct 2013 02:08:14 -0400 Message-ID: <526DBEAA.4030707@linaro.org> Date: Sun, 27 Oct 2013 18:32:26 -0700 From: Kevin Hilman User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Stephen Boyd , Frederic Weisbecker CC: linux-kernel@vger.kernel.org, mingo@kernel.org, hpa@zytor.com, linux-arm-kernel@lists.infradead.org, rmk@arm.linux.org.uk, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting References: <20131016121416.GD12773@localhost.localdomain> <20131018163740.GA21983@codeaurora.org> In-Reply-To: <20131018163740.GA21983@codeaurora.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Stephen, On 10/18/2013 09:37 AM, Stephen Boyd wrote: > On 10/16, Frederic Weisbecker wrote: >> On Thu, Oct 03, 2013 at 06:58:03AM -0700, tip-bot for Kevin Hilman wrote: >>> Commit-ID: 31c1fc8187158cb80ccd57c19e024c55af901797 >>> Gitweb: http://git.kernel.org/tip/31c1fc8187158cb80ccd57c19e024c55af901797 >>> Author: Kevin Hilman >>> AuthorDate: Mon, 16 Sep 2013 15:28:22 -0700 >>> Committer: Frederic Weisbecker >>> CommitDate: Mon, 30 Sep 2013 15:37:05 +0200 >>> >>> ARM: Kconfig: allow full nohz CPU accounting >>> >>> With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN, >>> allow ARM platforms to enable it. Since VIRT_CPU_ACCOUNTING_GEN is a >>> dependency for full NO_HZ, this allows ARM platforms to enable full >>> NO_HZ as well. >> >> I realize that arm doesn't implement irq work raise. It hooks on the >> timer to execute pending irq work. You'll need to implement arch_irq_work_raise() >> and implement some sort of self IPI to trigger irq work. The full dynticks subsystem >> relies on that to work correctly. It often use that to re-evaluate and possibly restart >> the tick after scheduler, posix timer updates, etc... >> >> That notwithstanding that if you have no tick, tick based irq work can't >> work. >> > > Something like this? The only problem is that this latches on to > the SMP support for IPIs. If CONFIG_SMP is disabled we won't get > arch_irq_work_raise() but perhaps that isn't so big of a deal? Or > we should think about exposing IPI support to UP systems on ARM. Care to submit a proper patch for this to LAKML? or if you prefer I can do it (keeping your authorship.) We need this for proper full NOHZ support on ARM. Thanks. Kevin