Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753460Ab2B0KMb (ORCPT ); Mon, 27 Feb 2012 05:12:31 -0500 Received: from casper.infradead.org ([85.118.1.10]:58097 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752488Ab2B0KMa convert rfc822-to-8bit (ORCPT ); Mon, 27 Feb 2012 05:12:30 -0500 Message-ID: <1330337535.11248.45.camel@twins> Subject: Re: [PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM From: Peter Zijlstra To: Dmitry Antipov Cc: linux-kernel@vger.kernel.org, Russell King , Rusty Russell , Ingo Molnar , Yong Zhang , Venki Pallipadi , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linaro-dev@lists.linaro.org, patches@linaro.org, Venkatesh Pallipadi Date: Mon, 27 Feb 2012 11:12:15 +0100 In-Reply-To: <1329717859-19378-1-git-send-email-dmitry.antipov@linaro.org> References: <1329717859-19378-1-git-send-email-dmitry.antipov@linaro.org> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2959 Lines: 89 On Mon, 2012-02-20 at 10:04 +0400, Dmitry Antipov wrote: > Generalize CONFIG_IRQ_TIME_ACCOUNTING between X86 and > ARM, move "noirqtime=" option to common debugging code. > For a bit of backward compatibility, X86-specific option > "tsc=noirqtime" is preserved, but issues a warning. > > Suggested-by: Yong Zhang > Suggested-by: Russell King > Suggested-by: Ingo Molnar > Acked-by: Venkatesh Pallipadi > Signed-off-by: Dmitry Antipov Thanks for Cc'ing me (maintainer) and Venki (original author of the stuff) :-) > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 7d379a6..9b13f79 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1961,13 +1961,16 @@ extern void sched_clock_idle_wakeup_event(u64 delta_ns); > #endif > > #ifdef CONFIG_IRQ_TIME_ACCOUNTING > -/* > - * An i/f to runtime opt-in for irq time accounting based off of sched_clock. > - * The reason for this explicit opt-in is not to have perf penalty with > - * slow sched_clocks. > - */ > -extern void enable_sched_clock_irqtime(void); > -extern void disable_sched_clock_irqtime(void); > +extern int sched_clock_irqtime; > +static inline void enable_sched_clock_irqtime(void) > +{ > + if (sched_clock_irqtime == -1) > + sched_clock_irqtime = 1; > +} > +static inline void disable_sched_clock_irqtime(void) > +{ > + sched_clock_irqtime = 0; > +} > #else > static inline void enable_sched_clock_irqtime(void) {} > static inline void disable_sched_clock_irqtime(void) {} Please keep them out-of-line, its not a fast path and it avoids having to expose the state variable. > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 5255c9d..4e7a197 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -757,18 +757,21 @@ static DEFINE_PER_CPU(u64, cpu_hardirq_time); > static DEFINE_PER_CPU(u64, cpu_softirq_time); > > static DEFINE_PER_CPU(u64, irq_start_time); > -static int sched_clock_irqtime; > > -void enable_sched_clock_irqtime(void) > -{ > - sched_clock_irqtime = 1; > -} > +/* > + * -1 if not initialized, 0 if disabled with "noirqtime" kernel option > + * or after unstable clock was detected, 1 if enabled and active. > + */ You forgot to explain what you need the tri-state for. > +__read_mostly int sched_clock_irqtime = -1; > > -void disable_sched_clock_irqtime(void) > +static int __init irqtime_setup(char *str) > { > sched_clock_irqtime = 0; > + return 1; > } > > +__setup("noirqtime", irqtime_setup); > + > #ifndef CONFIG_64BIT > static DEFINE_PER_CPU(seqcount_t, irq_time_seq); Other than that no real objections.. I guess. -- 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/