Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753477AbaA0MDv (ORCPT ); Mon, 27 Jan 2014 07:03:51 -0500 Received: from e8.ny.us.ibm.com ([32.97.182.138]:41665 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751827AbaA0MDs (ORCPT ); Mon, 27 Jan 2014 07:03:48 -0500 Message-ID: <52E64A37.4090405@linux.vnet.ibm.com> Date: Mon, 27 Jan 2014 17:29:51 +0530 From: Preeti U Murthy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Nicolas Pitre CC: Russell King , Catalin Marinas , Benjamin Herrenschmidt , Paul Mundt , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , "Rafael J. Wysocki" , Daniel Lezcano , linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 6/9] PPC: remove redundant cpuidle_idle_call() References: <1390802904-28399-1-git-send-email-nicolas.pitre@linaro.org> <1390802904-28399-7-git-send-email-nicolas.pitre@linaro.org> In-Reply-To: <1390802904-28399-7-git-send-email-nicolas.pitre@linaro.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14012712-0320-0000-0000-0000024AB78E Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nicolas, On 01/27/2014 11:38 AM, Nicolas Pitre wrote: > The core idle loop now takes care of it. However a few things need > checking: > > - Invocation of cpuidle_idle_call() in pseries_lpar_idle() happened > through arch_cpu_idle() and was therefore always preceded by a call > to ppc64_runlatch_off(). To preserve this property now that > cpuidle_idle_call() is invoked directly from core code, a call to > ppc64_runlatch_off() has been added to idle_loop_prolog() in > platforms/pseries/processor_idle.c. > > - Similarly, cpuidle_idle_call() was followed by ppc64_runlatch_off() > so a call to the later has been added to idle_loop_epilog(). > > - And since arch_cpu_idle() always made sure to re-enable IRQs if they > were not enabled, this is now > done in idle_loop_epilog() as well. > > The above was made in order to keep the execution flow close to the > original. I don't know if that was strictly necessary. Someone well > aquainted with the platform details might find some room for possible > optimizations. > > Signed-off-by: Nicolas Pitre > --- > arch/powerpc/platforms/pseries/processor_idle.c | 5 ++++ > arch/powerpc/platforms/pseries/setup.c | 34 ++++++++++--------------- > 2 files changed, 19 insertions(+), 20 deletions(-) > > diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c > index a166e38bd6..72ddfe3d2f 100644 > --- a/arch/powerpc/platforms/pseries/processor_idle.c > +++ b/arch/powerpc/platforms/pseries/processor_idle.c > @@ -33,6 +33,7 @@ static struct cpuidle_state *cpuidle_state_table; > > static inline void idle_loop_prolog(unsigned long *in_purr) > { > + ppc64_runlatch_off(); > *in_purr = mfspr(SPRN_PURR); > /* > * Indicate to the HV that we are idle. Now would be > @@ -49,6 +50,10 @@ static inline void idle_loop_epilog(unsigned long in_purr) > wait_cycles += mfspr(SPRN_PURR) - in_purr; > get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); > get_lppaca()->idle = 0; > + > + if (irqs_disabled()) > + local_irq_enable(); > + ppc64_runlatch_on(); > } > > static int snooze_loop(struct cpuidle_device *dev, > diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c > index c1f1908587..7604c19d54 100644 > --- a/arch/powerpc/platforms/pseries/setup.c > +++ b/arch/powerpc/platforms/pseries/setup.c > @@ -39,7 +39,6 @@ > #include > #include > #include > -#include > #include > #include > > @@ -356,29 +355,24 @@ early_initcall(alloc_dispatch_log_kmem_cache); > > static void pseries_lpar_idle(void) > { > - /* This would call on the cpuidle framework, and the back-end pseries > - * driver to go to idle states > + /* > + * Default handler to go into low thread priority and possibly > + * low power mode by cedeing processor to hypervisor > */ > - if (cpuidle_idle_call()) { > - /* On error, execute default handler > - * to go into low thread priority and possibly > - * low power mode by cedeing processor to hypervisor > - */ > > - /* Indicate to hypervisor that we are idle. */ > - get_lppaca()->idle = 1; > + /* Indicate to hypervisor that we are idle. */ > + get_lppaca()->idle = 1; > > - /* > - * Yield the processor to the hypervisor. We return if > - * an external interrupt occurs (which are driven prior > - * to returning here) or if a prod occurs from another > - * processor. When returning here, external interrupts > - * are enabled. > - */ > - cede_processor(); > + /* > + * Yield the processor to the hypervisor. We return if > + * an external interrupt occurs (which are driven prior > + * to returning here) or if a prod occurs from another > + * processor. When returning here, external interrupts > + * are enabled. > + */ > + cede_processor(); > > - get_lppaca()->idle = 0; > - } > + get_lppaca()->idle = 0; > } > > /* > Reviewed-by: Preeti U Murthy The consequence of this would be for other Power platforms like PowerNV, we will need to invoke ppc_runlatch_off() and ppc_runlatch_on() in each of the idle routines since the idle_loop_prologue() and idle_loop_epilogue() are not invoked by them, but we will take care of this. Regards Preeti U Murthy -- 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/