From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: Re: [PATCH 0/4] time: dynamic irq affinity Date: Mon, 11 Mar 2013 15:59:21 +0530 Message-ID: <513DB201.80503@ti.com> References: <1361917047-29230-1-git-send-email-daniel.lezcano@linaro.org> <513CC404.6000200@ti.com> <513CCF60.6060406@linaro.org> <513D4E79.5090307@ti.com> <513D9896.2010304@linaro.org> <513DA009.9080601@ti.com> <513DA3BD.4070003@stericsson.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:52957 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752501Ab3CKK2A (ORCPT ); Mon, 11 Mar 2013 06:28:00 -0400 In-Reply-To: <513DA3BD.4070003@stericsson.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Rickard Andersson Cc: Daniel Lezcano , "john.stultz@linaro.org" , "tglx@linutronix.de" , "viresh.kumar@linaro.org" , "jacob.jun.pan@linux.intel.com" , "linux-arm-kernel@lists.infradead.org" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linaro-kernel@lists.linaro.org" , "patches@linaro.org" , Linus WALLEIJ On Monday 11 March 2013 02:58 PM, Rickard Andersson wrote: > On 03/11/2013 10:12 AM, Santosh Shilimkar wrote: >> On Monday 11 March 2013 02:10 PM, Daniel Lezcano wrote: >>> On 03/11/2013 04:24 AM, Santosh Shilimkar wrote: >>>> On Sunday 10 March 2013 11:52 PM, Daniel Lezcano wrote: >>> [ ... ] >>> >>>>> I don't think it is the case for all the ARM platforms, at least we >>>>> tested it on vexpress TC2 and u8500, and the number of IPI were reduced >>>>> very significantly increasing the idle time for cpu0. TC2 will need >>>>> another optimization on another area for the idle wake up to gain real >>>>> improvements. >>>>> >>>> You are missing my point. TC2 can be an exception since the SGI can wakeup >>>> CPUs even from low power states where local timer's are stalled. Is that >>>> the case with U8500 ? >>> Well, the cpuidle driver is not going into a deep idle state to check >>> this out. >>> >>> AFAICT this board has a specific firmware with the PRCMU (a device >>> managing the power on the board) and it replaces the GIC when going to >>> deep idle state, especially by reconnecting the GIC to the A9 cores >>> automatically when an interrupt occurs. >>> >> But most likely it will be limited to peripheral interrupts. SGI's >> are per-cpu irq's so you need to check that part. >> > In the U8500 case, when the first CPU is woken up it will work ok for that CPU to send an IPI to the other CPU. > Nice. So in your case, IPI's will always work as long as one of the CPU is active. Regards Santosh