From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753524Ab3CKJ3P (ORCPT ); Mon, 11 Mar 2013 05:29:15 -0400 Received: from eu1sys200aog104.obsmtp.com ([207.126.144.117]:60781 "EHLO eu1sys200aog104.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752724Ab3CKJ3O (ORCPT ); Mon, 11 Mar 2013 05:29:14 -0400 Message-ID: <513DA3BD.4070003@stericsson.com> Date: Mon, 11 Mar 2013 10:28:29 +0100 From: Rickard Andersson User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110921 Lightning/1.0b2 Thunderbird/3.1.15 MIME-Version: 1.0 To: Santosh Shilimkar 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 Subject: Re: [PATCH 0/4] time: dynamic irq affinity 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> In-Reply-To: <513DA009.9080601@ti.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. BR Rickard