From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753077AbbC3SvZ (ORCPT ); Mon, 30 Mar 2015 14:51:25 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:53380 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752107AbbC3SvW (ORCPT ); Mon, 30 Mar 2015 14:51:22 -0400 From: "Rafael J. Wysocki" To: Viresh Kumar Cc: Shilpasri G Bhat , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List Subject: Re: [PATCH v3] cpufreq: powernv: Report cpu frequency throttling Date: Mon, 30 Mar 2015 21:15:34 +0200 Message-ID: <2339245.XXG4qaq6pt@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.19.0+; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: <1427441523-5189-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, March 27, 2015 01:10:46 PM Viresh Kumar wrote: > On 27 March 2015 at 13:02, Shilpasri G Bhat > wrote: > > The power and thermal safety of the system is taken care by an > > On-Chip-Controller (OCC) which is real-time subsystem embedded within > > the POWER8 processor. OCC continuously monitors the memory and core > > temperature, the total system power, state of power supply and fan. > > > > The cpu frequency can be throttled by OCC for the following reasons: > > 1)If a processor crosses its power and temperature limit then OCC will > > lower its Pmax to reduce the frequency and voltage. > > 2)If OCC crashes then the system is forced to Psafe frequency. > > 3)If OCC fails to recover then the kernel is not allowed to do any > > further frequency changes and the chip will remain in Psafe. > > > > The user can see a drop in performance when frequency is throttled and > > is unaware of throttling. So detect and report such a condition so > > that user can check the OCC status to reboot the system or check for > > power supply or fan failures. > > > > The current status of the core is read from Power Management Status > > Register(PMSR) to check if any of the throttling condition is occurred > > and the appropriate throttling message is reported. > > > > Signed-off-by: Shilpasri G Bhat > > --- > > Changes from V2: > > -Changed commit log to add more details. > > -Fixed multi-line comment to proper format > > > > Changes from V1: Removed unused value of PMCR register > > > > drivers/cpufreq/powernv-cpufreq.c | 40 ++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 39 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c > > index 2dfd4fd..0eb89a9 100644 > > --- a/drivers/cpufreq/powernv-cpufreq.c > > +++ b/drivers/cpufreq/powernv-cpufreq.c > > @@ -36,7 +36,7 @@ > > #define POWERNV_MAX_PSTATES 256 > > > > static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; > > -static bool rebooting; > > +static bool rebooting, throttled; > > > > /* > > * Note: The set of pstates consists of contiguous integers, the > > @@ -294,6 +294,41 @@ 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) > > +{ > > + unsigned long pmsr; > > + int pmsr_pmax, pmsr_lp; > > + > > + pmsr = get_pmspr(SPRN_PMSR); > > + > > + /* Check for Pmax Capping */ > > + pmsr_pmax = (s8)((pmsr >> 32) & 0xFF); > > + if (pmsr_pmax != powernv_pstate_info.max) { > > + throttled = true; > > + pr_warn("Cpu %d Pmax is reduced to %d\n", cpu, pmsr_pmax); > > + } > > + > > + /* > > + * Check for Psafe by reading LocalPstate > > + * or check if Psafe_mode_active- 34th bit is set in PMSR. > > + */ > > + pmsr_lp = (s8)((pmsr >> 48) & 0xFF); > > + if ((pmsr_lp < powernv_pstate_info.min) || ((pmsr >> 30) & 1)) { > > + throttled = true; > > + pr_warn("Cpu %d in Psafe %d PMSR[34]=%lx\n", cpu, > > + pmsr_lp, ((pmsr >> 30) & 1)); > > + } > > + > > + /* Check if SPR_EM_DISABLED- 33rd bit is set in PMSR */ > > + if ((pmsr >> 31) & 1) { > > + throttled = true; > > + pr_warn("Frequency management disabled cpu %d PMSR[33]=%lx\n", > > + cpu, ((pmsr >> 31) & 1)); > > + } > > + if (throttled) > > + pr_warn("Cpu Frequency is throttled\n"); > > +} > > + > > /* > > * powernv_cpufreq_target_index: Sets the frequency corresponding to > > * the cpufreq table entry indexed by new_index on the cpus in the > > @@ -307,6 +342,9 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, > > if (unlikely(rebooting) && new_index != get_nominal_index()) > > return 0; > > > > + if (!throttled) > > + powernv_cpufreq_throttle_check(smp_processor_id()); > > + > > freq_data.pstate_id = powernv_freqs[new_index].driver_data; > > Acked-by: Viresh Kumar Queued up for 4.1, thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.