From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e7.ny.us.ibm.com (e7.ny.us.ibm.com [32.97.182.137]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 49D5C2C009E for ; Mon, 27 Jan 2014 23:03:52 +1100 (EST) Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 27 Jan 2014 07:03:47 -0500 Received: from b01cxnp23034.gho.pok.ibm.com (b01cxnp23034.gho.pok.ibm.com [9.57.198.29]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id A6A7438C8047 for ; Mon, 27 Jan 2014 07:03:45 -0500 (EST) Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by b01cxnp23034.gho.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s0RC3jdY7143868 for ; Mon, 27 Jan 2014 12:03:45 GMT Received: from d01av04.pok.ibm.com (localhost [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s0RC3ggI008180 for ; Mon, 27 Jan 2014 07:03:45 -0500 Message-ID: <52E64A37.4090405@linux.vnet.ibm.com> Date: Mon, 27 Jan 2014 17:29:51 +0530 From: Preeti U Murthy MIME-Version: 1.0 To: Nicolas Pitre 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 Cc: linaro-kernel@lists.linaro.org, Russell King , linux-pm@vger.kernel.org, Peter Zijlstra , Catalin Marinas , Daniel Lezcano , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org, Paul Mundt , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Ingo Molnar , linux-arm-kernel@lists.infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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