From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 680CE1A066D for ; Tue, 5 May 2015 16:06:59 +1000 (AEST) Received: from e28smtp01.in.ibm.com (e28smtp01.in.ibm.com [122.248.162.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id B992B140D2E for ; Tue, 5 May 2015 16:06:58 +1000 (AEST) Received: from /spool/local by e28smtp01.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 5 May 2015 11:36:54 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id E14FF3940048 for ; Tue, 5 May 2015 11:36:50 +0530 (IST) Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t4566Zbx49545250 for ; Tue, 5 May 2015 11:36:36 +0530 Received: from d28av05.in.ibm.com (localhost [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t4566Y9U017385 for ; Tue, 5 May 2015 11:36:35 +0530 Message-ID: <55485DE9.4070609@linux.vnet.ibm.com> Date: Tue, 05 May 2015 11:36:33 +0530 From: Shilpasri G Bhat MIME-Version: 1.0 To: Preeti U Murthy , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/6] cpufreq: poowernv: Handle throttling due to Pmax capping at chip level References: <1430729652-14813-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <1430729652-14813-2-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <55483E4B.4080405@linux.vnet.ibm.com> In-Reply-To: <55483E4B.4080405@linux.vnet.ibm.com> Content-Type: text/plain; charset=iso-8859-6 Cc: viresh.kumar@linaro.org, rjw@rjwysocki.net, linux-pm@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Preeti, On 05/05/2015 09:21 AM, Preeti U Murthy wrote: > Hi Shilpa, > > On 05/04/2015 02:24 PM, Shilpasri G Bhat wrote: >> The On-Chip-Controller(OCC) can throttle cpu frequency by reducing the >> max allowed frequency for that chip if the chip exceeds its power or >> temperature limits. As Pmax capping is a chip level condition report >> this throttling behavior at chip level and also do not set the global >> 'throttled' on Pmax capping instead set the per-chip throttled >> variable. Report unthrottling if Pmax is restored after throttling. >> >> This patch adds a structure to store chip id and throttled state of >> the chip. >> >> Signed-off-by: Shilpasri G Bhat >> --- >> drivers/cpufreq/powernv-cpufreq.c | 59 ++++++++++++++++++++++++++++++++++++--- >> 1 file changed, 55 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c >> index ebef0d8..d0c18c9 100644 >> --- a/drivers/cpufreq/powernv-cpufreq.c >> +++ b/drivers/cpufreq/powernv-cpufreq.c >> @@ -27,6 +27,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -42,6 +43,13 @@ >> static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; >> static bool rebooting, throttled; >> >> +static struct chip { >> + unsigned int id; >> + bool throttled; >> +} *chips; >> + >> +static int nr_chips; >> + >> /* >> * Note: The set of pstates consists of contiguous integers, the >> * smallest of which is indicated by powernv_pstate_info.min, the >> @@ -301,22 +309,33 @@ static inline unsigned int get_nominal_index(void) >> static void powernv_cpufreq_throttle_check(unsigned int cpu) >> { >> unsigned long pmsr; >> - int pmsr_pmax, pmsr_lp; >> + int pmsr_pmax, pmsr_lp, i; >> >> pmsr = get_pmspr(SPRN_PMSR); >> >> + for (i = 0; i < nr_chips; i++) >> + if (chips[i].id == cpu_to_chip_id(cpu)) >> + break; >> + >> /* Check for Pmax Capping */ >> pmsr_pmax = (s8)PMSR_MAX(pmsr); >> if (pmsr_pmax != powernv_pstate_info.max) { >> - throttled = true; >> - pr_info("CPU %d Pmax is reduced to %d\n", cpu, pmsr_pmax); >> - pr_info("Max allowed Pstate is capped\n"); >> + if (chips[i].throttled) >> + goto next; >> + chips[i].throttled = true; >> + pr_info("CPU %d on Chip %u has Pmax reduced to %d\n", cpu, >> + chips[i].id, pmsr_pmax); >> + } else if (chips[i].throttled) { >> + chips[i].throttled = false; > > Is this check on pmax sufficient to indicate that the chip is unthrottled ? Unthrottling due to Pmax uncapping here is specific to a chip. So it is sufficient to decide throttling/unthrottling when OCC is active for that chip. > >> + pr_info("CPU %d on Chip %u has Pmax restored to %d\n", cpu, >> + chips[i].id, pmsr_pmax); >> } >> >> /* >> * Check for Psafe by reading LocalPstate >> * or check if Psafe_mode_active is set in PMSR. >> */ >> +next: >> pmsr_lp = (s8)PMSR_LP(pmsr); >> if ((pmsr_lp < powernv_pstate_info.min) || >> (pmsr & PMSR_PSAFE_ENABLE)) { >> @@ -414,6 +433,33 @@ static struct cpufreq_driver powernv_cpufreq_driver = { >> .attr = powernv_cpu_freq_attr, > > What about the situation where although occ is active, this particular > chip has been throttled and we end up repeatedly reporting "pstate set > to safe" and "frequency control disabled from OS" ? Should we not have a > check on (chips[i].throttled) before reporting an anomaly for these two > scenarios as well just like you have for pmsr_pmax ? We will not have "Psafe" and "frequency control disabled" repeatedly printed because of global variable 'throttled', which is set to true on passing any of these two conditions. It is quite unlikely behavior to have only one chip in "Psafe" or "frequency control disabled" state. These two conditions are most likely to happen during an OCC reset cycle which will occur across all chips. Thanks and Regards, Shilpa