Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756274Ab3JRQho (ORCPT ); Fri, 18 Oct 2013 12:37:44 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:47676 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751961Ab3JRQhm (ORCPT ); Fri, 18 Oct 2013 12:37:42 -0400 Date: Fri, 18 Oct 2013 09:37:40 -0700 From: Stephen Boyd To: 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, khilman@linaro.org, linux-tip-commits@vger.kernel.org Subject: Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting Message-ID: <20131018163740.GA21983@codeaurora.org> References: <20131016121416.GD12773@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131016121416.GD12773@localhost.localdomain> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3821 Lines: 114 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. ----8<----- arch/arm/include/asm/hardirq.h | 2 +- arch/arm/kernel/smp.c | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h index 2740c2a2..3d7351c 100644 --- a/arch/arm/include/asm/hardirq.h +++ b/arch/arm/include/asm/hardirq.h @@ -5,7 +5,7 @@ #include #include -#define NR_IPI 6 +#define NR_IPI 7 typedef struct { unsigned int __softirq_pending; diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 72024ea..bf9a0d6d 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include @@ -66,6 +67,7 @@ enum ipi_msg_type { IPI_CALL_FUNC, IPI_CALL_FUNC_SINGLE, IPI_CPU_STOP, + IPI_IRQ_WORK, }; static DECLARE_COMPLETION(cpu_running); @@ -448,6 +450,13 @@ void arch_send_call_function_single_ipi(int cpu) smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE); } +#ifdef CONFIG_IRQ_WORK +void arch_irq_work_raise(void) +{ + smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK); +} +#endif + static const char *ipi_types[NR_IPI] = { #define S(x,s) [x] = s S(IPI_WAKEUP, "CPU wakeup interrupts"), @@ -456,6 +465,7 @@ static const char *ipi_types[NR_IPI] = { S(IPI_CALL_FUNC, "Function call interrupts"), S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"), S(IPI_CPU_STOP, "CPU stop interrupts"), + S(IPI_IRQ_WORK, "IRQ work interrupts"), }; void show_ipi_list(struct seq_file *p, int prec) @@ -565,6 +575,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs) irq_exit(); break; +#ifdef CONFIG_IRQ_WORK + case IPI_IRQ_WORK: + irq_enter(); + irq_work_run(); + irq_exit(); + break; +#endif + default: printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/