Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752635AbbEGMTf (ORCPT ); Thu, 7 May 2015 08:19:35 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:52332 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751442AbbEGMTc (ORCPT ); Thu, 7 May 2015 08:19:32 -0400 Message-ID: <554B584A.3030507@linux.vnet.ibm.com> Date: Thu, 07 May 2015 17:49:22 +0530 From: Preeti U Murthy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Shilpasri G Bhat , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org CC: viresh.kumar@linaro.org, rjw@rjwysocki.net, linux-pm@vger.kernel.org Subject: Re: [PATCH v3 4/6] cpufreq: powernv: Call throttle_check() on receiving OCC_THROTTLE References: <1430729652-14813-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <1430729652-14813-5-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <55484072.5060400@linux.vnet.ibm.com> <5548641C.5090208@linux.vnet.ibm.com> <5548824C.2030602@linux.vnet.ibm.com> In-Reply-To: <5548824C.2030602@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15050712-0033-0000-0000-00000470E4BE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5907 Lines: 164 On 05/05/2015 02:11 PM, Preeti U Murthy wrote: > On 05/05/2015 12:03 PM, Shilpasri G Bhat wrote: >> Hi Preeti, >> >> On 05/05/2015 09:30 AM, Preeti U Murthy wrote: >>> Hi Shilpa, >>> >>> On 05/04/2015 02:24 PM, Shilpasri G Bhat wrote: >>>> Re-evaluate the chip's throttled state on recieving OCC_THROTTLE >>>> notification by executing *throttle_check() on any one of the cpu on >>>> the chip. This is a sanity check to verify if we were indeed >>>> throttled/unthrottled after receiving OCC_THROTTLE notification. >>>> >>>> We cannot call *throttle_check() directly from the notification >>>> handler because we could be handling chip1's notification in chip2. So >>>> initiate an smp_call to execute *throttle_check(). We are irq-disabled >>>> in the notification handler, so use a worker thread to smp_call >>>> throttle_check() on any of the cpu in the chipmask. >>> >>> I see that the first patch takes care of reporting *per-chip* throttling >>> for pmax capping condition. But where are we taking care of reporting >>> "pstate set to safe" and "freq control disabled" scenarios per-chip ? >>> >> >> IMO let us not have "psafe" and "freq control disabled" states managed per-chip. >> Because when the above two conditions occur it is likely to happen across all >> chips during an OCC reset cycle. So I am setting 'throttled' to false on >> OCC_ACTIVE and re-verifying if it actually is the case by invoking >> *throttle_check(). > > Alright like I pointed in the previous reply, a comment to indicate that > psafe and freq control disabled conditions will fail when occ is > inactive and that all chips face the consequence of this will help. >From your explanation on the thread of the first patch of this series, this will not be required. So, Reviewed-by: Preeti U Murthy Regards Preeti U Murthy > >> >>>> >>>> Signed-off-by: Shilpasri G Bhat >>>> --- >>>> drivers/cpufreq/powernv-cpufreq.c | 28 ++++++++++++++++++++++++++-- >>>> 1 file changed, 26 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c >>>> index 9268424..9618813 100644 >>>> --- a/drivers/cpufreq/powernv-cpufreq.c >>>> +++ b/drivers/cpufreq/powernv-cpufreq.c >>>> @@ -50,6 +50,8 @@ static bool rebooting, throttled, occ_reset; >>>> static struct chip { >>>> unsigned int id; >>>> bool throttled; >>>> + cpumask_t mask; >>>> + struct work_struct throttle; >>>> } *chips; >>>> >>>> static int nr_chips; >>>> @@ -310,8 +312,9 @@ static inline unsigned int get_nominal_index(void) >>>> return powernv_pstate_info.max - powernv_pstate_info.nominal; >>>> } >>>> >>>> -static void powernv_cpufreq_throttle_check(unsigned int cpu) >>>> +static void powernv_cpufreq_throttle_check(void *data) >>>> { >>>> + unsigned int cpu = smp_processor_id(); >>>> unsigned long pmsr; >>>> int pmsr_pmax, pmsr_lp, i; >>>> >>>> @@ -373,7 +376,7 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, >>>> return 0; >>>> >>>> if (!throttled) >>>> - powernv_cpufreq_throttle_check(smp_processor_id()); >>>> + powernv_cpufreq_throttle_check(NULL); >>>> >>>> freq_data.pstate_id = powernv_freqs[new_index].driver_data; >>>> >>>> @@ -418,6 +421,14 @@ static struct notifier_block powernv_cpufreq_reboot_nb = { >>>> .notifier_call = powernv_cpufreq_reboot_notifier, >>>> }; >>>> >>>> +void powernv_cpufreq_work_fn(struct work_struct *work) >>>> +{ >>>> + struct chip *chip = container_of(work, struct chip, throttle); >>>> + >>>> + smp_call_function_any(&chip->mask, >>>> + powernv_cpufreq_throttle_check, NULL, 0); >>>> +} >>>> + >>>> static char throttle_reason[][30] = { >>>> "No throttling", >>>> "Power Cap", >>>> @@ -433,6 +444,7 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb, >>>> struct opal_msg *occ_msg = msg; >>>> uint64_t token; >>>> uint64_t chip_id, reason; >>>> + int i; >>>> >>>> if (msg_type != OPAL_MSG_OCC) >>>> return 0; >>>> @@ -466,6 +478,10 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb, >>>> occ_reset = false; >>>> throttled = false; >>>> pr_info("OCC: Active\n"); >>>> + >>>> + for (i = 0; i < nr_chips; i++) >>>> + schedule_work(&chips[i].throttle); >>>> + >>>> return 0; >>>> } >>>> >>>> @@ -476,6 +492,12 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb, >>>> else if (!reason) >>>> pr_info("OCC: Chip %u %s\n", (unsigned int)chip_id, >>>> throttle_reason[reason]); >>>> + else >>>> + return 0; >>> >>> Why the else section ? The code can never reach here, can it ? >> >> When reason > 5 , we dont want to handle it. > > Of course! My bad! >> >>> >>>> + >>>> + for (i = 0; i < nr_chips; i++) >>>> + if (chips[i].id == chip_id) >>>> + schedule_work(&chips[i].throttle); >>>> } >>> >>> Should we not do this only when we get unthrottled so as to cross verify >>> if it is indeed the case ? In case of throttling notification, opal's >>> verdict is final and there is no need to cross verify right ? >> >> Two reasons for invoking *throttle_check() on throttling: >> 1) We just got to know the reason and not the Pmax value we are getting >> throttled to. >> 2) It could be a spurious message caused due to late/lost delivery. My point >> here is let us not completely rely on the notification to declare throttling >> unless we verify it from reading PMSR. > > Sounds good. > > Regards > Preeti U Murthy > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > -- 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/