PM: Intel PowerClamp driver
Subsystems (4)
v6 cover PM: Intel PowerClamp driver
v6 changes:
- clamp module parameters duration and window size, reword warning messages when input parameters are out of range.
We have done some experiment with idle injection on Intel platforms. The idea is to use the increasingly power efficient package level C-states for power capping and passive thermal control.
Documentation is included in the patch to explain the theory of operation, performance implication, calibration, scalability, and user interface. Please refer to the following file for more details.
Documentation/thermal/intel_powerclamp.txt
Arjan van de Ven created the original idea and driver, I have been refining driver in hope that they can be to be useful beyond a proof of concept.
Jacob Pan (3):
tick: export nohz tick idle symbols for module use x86/nmi: export local_touch_nmi() symbol for modules
PM: Introduce Intel PowerClamp Driver
Documentation/thermal/intel_powerclamp.txt | 307 +++++++++++ arch/x86/kernel/nmi.c | 1 + drivers/thermal/Kconfig | 10 + drivers/thermal/Makefile | 2 + drivers/thermal/intel_powerclamp.c | 788 ++++++++++++++++++++++++++++ kernel/time/tick-sched.c | 2 + 6 files changed, 1110 insertions(+) create mode 100644 Documentation/thermal/intel_powerclamp.txt create mode 100644 drivers/thermal/intel_powerclamp.c
Signature · 1 line
1.7.9.5
PATCH v6 1/3 tick: export nohz tick idle symbols for module use
Allow drivers such as intel_powerclamp to use these apis for turning on/off ticks during idle.
Signed-off-by Jacob Pan <[email protected]>
--- kernel/time/tick-sched.c | 2 ++ 1 file changed, 2 insertions(+)
kernel/time/tick-sched.c +2 -0
@@ -553,6 +553,7 @@ void tick_nohz_idle_enter(void)local_irq_enable (); } +EXPORT_SYMBOL_GPL (tick_nohz_idle_enter);/** * tick_nohz_irq_exit - update next tick event from interrupt exit
@@ -681,6 +682,7 @@ void tick_nohz_idle_exit(void)local_irq_enable (); } +EXPORT_SYMBOL_GPL (tick_nohz_idle_exit);static int tick_nohz_reprogram (struct tick_sched *ts,ktime_t now) {
Signature · 1 line
1.7.9.5
Re: [PATCH v6 1/3] tick: export nohz tick idle symbols for module use
Quoted 4 lines · Jacob Pan
Allow drivers such as
intel_powerclampto use these apis for turning on/off ticks during idle.Signed-off-by Jacob Pan <[email protected]>
applied to thermal -next.
thanks,
rui
Quoted 24 lines
--- kernel/time/tick-sched.c | 2 ++ 1 file changed, 2 insertions(+)kernel/time/tick-sched.c +2
-0@@ -553,6 +553,7 @@ void tick_nohz_idle_enter(void)local_irq_enable (); } +EXPORT_SYMBOL_GPL (tick_nohz_idle_enter);/** * tick_nohz_irq_exit - update next tick event from interrupt exit @@ -681,6 +682,7 @@ void tick_nohz_idle_exit(void)local_irq_enable (); } +EXPORT_SYMBOL_GPL (tick_nohz_idle_exit);static int tick_nohz_reprogram (struct tick_sched *ts,ktime_t now) {
PATCH v6 2/3 x86/nmi: export local_touch_nmi() symbol for modules
In reply to Jacob PanSigned-off-by Jacob Pan <[email protected]>
--- arch/x86/kernel/nmi.c | 1 + 1 file changed, 1 insertion(+)
arch/x86/kernel/nmi.c +1 -0
@@ -509,3 +509,4 @@ void local_touch_nmi(void) {__this_cpu_write (last_nmi_rip,0 ); } +EXPORT_SYMBOL_GPL (local_touch_nmi);
Signature · 1 line
1.7.9.5
Re: [PATCH v6 2/3] x86/nmi: export local_touch_nmi() symbol for modules
Quoted 1 line · Jacob Pan
Signed-off-by Jacob Pan <[email protected]>
applied to thermal -next.
thanks,
rui
Quoted 13 lines
--- arch/x86/kernel/nmi.c | 1 + 1 file changed, 1 insertion(+)arch/x86/kernel/nmi.c +1
-0@@ -509,3 +509,4 @@ void local_touch_nmi(void) {__this_cpu_write (last_nmi_rip,0 ); } +EXPORT_SYMBOL_GPL (local_touch_nmi);
PATCH v6 3/3 PM: Introduce Intel PowerClamp Driver
In reply to Jacob PanIntel PowerClamp driver performs synchronized idle injection across all online CPUs. The goal is to maintain a given package level C-state ratio.
Compared to other throttling methods already exist in the kernel, such as ACPI PAD (taking CPUs offline) and clock modulation, this is often more efficient in terms of performance per watt.
Please refer to Documentation/thermal/intel_powerclamp.txt for more details.
Signed-off-by Arjan van de Ven <[email protected]>
Signed-off-by Jacob Pan <[email protected]>
--- Documentation/thermal/intel_powerclamp.txt | 307 +++++++++++ drivers/thermal/Kconfig | 10 + drivers/thermal/Makefile | 2 + drivers/thermal/intel_powerclamp.c | 788 ++++++++++++++++++++++++++++ 4 files changed, 1107 insertions(+) create mode 100644 Documentation/thermal/intel_powerclamp.txt create mode 100644 drivers/thermal/intel_powerclamp.c
Documentation/thermal/intel_powerclamp.txt new file +307 -0
@@ -0,0 +1,307 @@ + ======================= + INTEL POWERCLAMP DRIVER + ======================= +By: Arjan van de Ven <[email protected]> + Jacob Pan <[email protected]> + +Contents: + (*) Introduction + - Goals and Objectives + + (*) Theory of Operation + - Idle Injection + - Calibration + + (*) Performance Analysis + - Effectiveness and Limitations + - Power vs Performance + - Scalability + - Calibration + - Comparison with Alternative Techniques + + (*) Usage and Interfaces + - Generic Thermal Layer (sysfs) + - Kernel APIs (TBD) + +============ +INTRODUCTION +============ + +Consider the situation where a system’s power consumption must be +reduced at runtime, due to power budget, thermal constraint, or noise +level, and where active cooling is not preferred. Software managed +passive power reduction must be performed to prevent the hardware +actions that are designed for catastrophic scenarios. + +Currently, P-states, T-states (clock modulation), and CPU offlining +are used for CPU throttling. + +On Intel CPUs, C-states provide effective power reduction, but so far +they’re only used opportunistically, based on workload. With the +development of intel_powerclamp driver, the method of synchronizing +idle injection across all online CPU threads was introduced. The goal +is to achieve forced and controllable C-state residency. + +Test/Analysis has been made in the areas of power, performance, +scalability, and user experience. In many cases, clear advantage is +shown over taking the CPU offline or modulating the CPU clock. + + +=================== +THEORY OF OPERATION +=================== + +Idle Injection +-------------- + +On modern Intel processors (Nehalem or later), package level C-state +residency is available in MSRs, thus also available to the kernel. + +These MSRs are: + #define MSR_PKG_C2_RESIDENCY 0x60D + #define MSR_PKG_C3_RESIDENCY 0x3F8 + #define MSR_PKG_C6_RESIDENCY 0x3F9 + #define MSR_PKG_C7_RESIDENCY 0x3FA + +If the kernel can also inject idle time to the system, then a +closed-loop control system can be established that manages package +level C-state. The intel_powerclamp driver is conceived as such a +control system, where the target set point is a user-selected idle +ratio (based on power reduction), and the error is the difference +between the actual package level C-state residency ratio and the target idle +ratio. + +Injection is controlled by high priority kernel threads, spawned for +each online CPU. + +These kernel threads, with SCHED_FIFO class, are created to perform +clamping actions of controlled duty ratio and duration. Each per-CPU +thread synchronizes its idle time and duration, based on the rounding +of jiffies, so accumulated errors can be prevented to avoid a jittery +effect. Threads are also bound to the CPU such that they cannot be +migrated, unless the CPU is taken offline. In this case, threads +belong to the offlined CPUs will be terminated immediately. + +Running as SCHED_FIFO and relatively high priority, also allows such +scheme to work for both preemptable and non-preemptable kernels. +Alignment of idle time around jiffies ensures scalability for HZ +values. This effect can be better visualized using a Perf timechart. +The following diagram shows the behavior of kernel thread +kidle_inject/cpu. During idle injection, it runs monitor/mwait idle +for a given "duration", then relinquishes the CPU to other tasks, +until the next time interval. + +The NOHZ schedule tick is disabled during idle time, but interrupts +are not masked. Tests show that the extra wakeups from scheduler tick +have a dramatic impact on the effectiveness of the powerclamp driver +on large scale systems (Westmere system with 80 processors). + +CPU0 + ____________ ____________ +kidle_inject/0 | sleep | mwait | sleep | + _________| |________| |_______ + duration +CPU1 + ____________ ____________ +kidle_inject/1 | sleep | mwait | sleep | + _________| |________| |_______ + ^ + | + | + roundup(jiffies, interval) + +Only one CPU is allowed to collect statistics and update global +control parameters. This CPU is referred to as the controlling CPU in +this document. The controlling CPU is elected at runtime, with a +policy that favors BSP, taking into account the possibility of a CPU +hot-plug. + +In terms of dynamics of the idle control system, package level idle +time is considered largely as a non-causal system where its behavior +cannot be based on the past or current input. Therefore, the +intel_powerclamp driver attempts to enforce the desired idle time +instantly as given input (target idle ratio). After injection, +powerclamp moniors the actual idle for a given time window and adjust +the next injection accordingly to avoid over/under correction. + +When used in a causal control system, such as a temperature control, +it is up to the user of this driver to implement algorithms where +past samples and outputs are included in the feedback. For example, a +PID-based thermal controller can use the powerclamp driver to +maintain a desired target temperature, based on integral and +derivative gains of the past samples. + + + +Calibration +----------- +During scalability testing, it is observed that synchronized actions +among CPUs become challenging as the number of cores grows. This is +also true for the ability of a system to enter package level C-states. + +To make sure the intel_powerclamp driver scales well, online +calibration is implemented. The goals for doing such a calibration +are: + +a) determine the effective range of idle injection ratio +b) determine the amount of compensation needed at each target ratio + +Compensation to each target ratio consists of two parts: + + a) steady state error compensation + This is to offset the error occurring when the system can + enter idle without extra wakeups (such as external interrupts). + + b) dynamic error compensation + When an excessive amount of wakeups occurs during idle, an + additional idle ratio can be added to quiet interrupts, by + slowing down CPU activities. + +A debugfs file is provided for the user to examine compensation +progress and results, such as on a Westmere system. +[jacob@nex01 ~]$ cat +/sys/kernel/debug/intel_powerclamp/powerclamp_calib +controlling cpu: 0 +pct confidence steady dynamic (compensation) +0 0 0 0 +1 1 0 0 +2 1 1 0 +3 3 1 0 +4 3 1 0 +5 3 1 0 +6 3 1 0 +7 3 1 0 +8 3 1 0 +... +30 3 2 0 +31 3 2 0 +32 3 1 0 +33 3 2 0 +34 3 1 0 +35 3 2 0 +36 3 1 0 +37 3 2 0 +38 3 1 0 +39 3 2 0 +40 3 3 0 +41 3 1 0 +42 3 2 0 +43 3 1 0 +44 3 1 0 +45 3 2 0 +46 3 3 0 +47 3 0 0 +48 3 2 0 +49 3 3 0 + +Calibration occurs during runtime. No offline method is available. +Steady state compensation is used only when confidence levels of all +adjacent ratios have reached satisfactory level. A confidence level +is accumulated based on clean data collected at runtime. Data +collected during a period without extra interrupts is considered +clean. + +To compensate for excessive amounts of wakeup during idle, additional +idle time is injected when such a condition is detected. Currently, +we have a simple algorithm to double the injection ratio. A possible +enhancement might be to throttle the offending IRQ, such as delaying +EOI for level triggered interrupts. But it is a challenge to be +non-intrusive to the scheduler or the IRQ core code. + + +CPU Online/Offline +------------------ +Per-CPU kernel threads are started/stopped upon receiving +notifications of CPU hotplug activities. The intel_powerclamp driver +keeps track of clamping kernel threads, even after they are migrated +to other CPUs, after a CPU offline event. + + +===================== +Performance Analysis +===================== +This section describes the general performance data collected on +multiple systems, including Westmere (80P) and Ivy Bridge (4P, 8P). + +Effectiveness and Limitations +----------------------------- +The maximum range that idle injection is allowed is capped at 50 +percent. As mentioned earlier, since interrupts are allowed during +forced idle time, excessive interrupts could result in less +effectiveness. The extreme case would be doing a ping -f to generated +flooded network interrupts without much CPU acknowledgement. In this +case, little can be done from the idle injection threads. In most +normal cases, such as scp a large file, applications can be throttled +by the powerclamp driver, since slowing down the CPU also slows down +network protocol processing, which in turn reduces interrupts. + +When control parameters change at runtime by the controlling CPU, it +may take an additional period for the rest of the CPUs to catch up +with the changes. During this time, idle injection is out of sync, +thus not able to enter package C- states at the expected ratio. But +this effect is minor, in that in most cases change to the target +ratio is updated much less frequently than the idle injection +frequency. + +Scalability +----------- +Tests also show a minor, but measurable, difference between the 4P/8P +Ivy Bridge system and the 80P Westmere server under 50% idle ratio. +More compensation is needed on Westmere for the same amount of +target idle ratio. The compensation also increases as the idle ratio +gets larger. The above reason constitutes the need for the +calibration code. + +On the IVB 8P system, compared to an offline CPU, powerclamp can +achieve up to 40% better performance per watt. (measured by a spin +counter summed over per CPU counting threads spawned for all running +CPUs). + +==================== +Usage and Interfaces +==================== +The powerclamp driver is registered to the generic thermal layer as a +cooling device. Currently, it’s not bound to any thermal zones. + +jacob@chromoly:/sys/class/thermal/cooling_device14$ grep . * +cur_state:0 +max_state:50 +type:intel_powerclamp + +Example usage: +- To inject 25% idle time +$ sudo sh -c "echo 25 > /sys/class/thermal/cooling_device80/cur_state +" + +If the system is not busy and has more than 25% idle time already, +then the powerclamp driver will not start idle injection. Using Top +will not show idle injection kernel threads. + +If the system is busy (spin test below) and has less than 25% natural +idle time, powerclamp kernel threads will do idle injection, which +appear running to the scheduler. But the overall system idle is still +reflected. In this example, 24.1% idle is shown. This helps the +system admin or user determine the cause of slowdown, when a +powerclamp driver is in action. + + +Tasks: 197 total, 1 running, 196 sleeping, 0 stopped, 0 zombie +Cpu(s): 71.2%us, 4.7%sy, 0.0%ni, 24.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st +Mem: 3943228k total, 1689632k used, 2253596k free, 74960k buffers +Swap: 4087804k total, 0k used, 4087804k free, 945336k cached + + PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND + 3352 jacob 20 0 262m 644 428 S 286 0.0 0:17.16 spin + 3341 root -51 0 0 0 0 D 25 0.0 0:01.62 kidle_inject/0 + 3344 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/3 + 3342 root -51 0 0 0 0 D 25 0.0 0:01.61 kidle_inject/1 + 3343 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/2 + 2935 jacob 20 0 696m 125m 35m S 5 3.3 0:31.11 firefox + 1546 root 20 0 158m 20m 6640 S 3 0.5 0:26.97 Xorg + 2100 jacob 20 0 1223m 88m 30m S 3 2.3 0:23.68 compiz + +Tests have shown that by using the powerclamp driver as a cooling +device, a PID based userspace thermal controller can manage to +control CPU temperature effectively, when no other thermal influence +is added. For example, a UltraBook user can compile the kernel under +certain temperature (below most active trip points).
drivers/thermal/Kconfig +10 -0
@@ -122,4 +122,14 @@ config DB8500_CPUFREQ_COOLING bound cpufreq cooling device turns active to set CPU frequency low to cool down the CPU. +config INTEL_POWERCLAMP + tristate "Intel PowerClamp idle injection driver" + depends on THERMAL + depends on X86 + depends on CPU_SUP_INTEL + help + Enable this to enable Intel PowerClamp idle injection driver. This + enforce idle time which results in more package C-state residency. The + user interface is exposed via generic thermal framework. + endif
drivers/thermal/Makefile +2 -0
@@ -18,3 +18,5 @@ obj-$(CONFIG_RCAR_THERMAL) += rcar_thermal.o obj-$(CONFIG_EXYNOS_THERMAL) += exynos_thermal.o obj-$(CONFIG_DB8500_THERMAL) += db8500_thermal.o obj-$(CONFIG_DB8500_CPUFREQ_COOLING) += db8500_cpufreq_cooling.o +obj-$(CONFIG_INTEL_POWERCLAMP) += intel_powerclamp.o +
drivers/thermal/intel_powerclamp.c new file +788 -0
788 lines not on this page · raw message
Signature · 1 line
1.7.9.5
Zhang Rui
reviewerRe: [PATCH v6 3/3] PM: Introduce Intel PowerClamp Driver
Hi, Jacob,
Quoted 100 lines · Jacob Pan
Intel PowerClamp driver performs synchronized idle injection across all online CPUs. The goal is to maintain a given package level C-state ratio.
Compared to other throttling methods already exist in the kernel, such as ACPI PAD (taking CPUs offline) and clock modulation, this is often more efficient in terms of performance per watt.
Please refer to
Documentation/thermal/intel_powerclamp.txtfor more details.Signed-off-by Arjan van de Ven <[email protected]>Signed-off-by Jacob Pan <[email protected]>--- Documentation/thermal/intel_powerclamp.txt | 307 +++++++++++ drivers/thermal/Kconfig | 10 + drivers/thermal/Makefile | 2 + drivers/thermal/intel_powerclamp.c | 788 ++++++++++++++++++++++++++++ 4 files changed, 1107 insertions(+) create mode 100644 Documentation/thermal/intel_powerclamp.txt create mode 100644 drivers/thermal/intel_powerclamp.cdrivers/thermal/Kconfig +10
-0@@ -122,4 +122,14 @@ config DB8500_CPUFREQ_COOLING bound cpufreq cooling device turns active to set CPU frequency low to cool down the CPU. +config INTEL_POWERCLAMP + tristate "Intel PowerClamp idle injection driver" + depends on THERMAL + depends on X86 + depends on CPU_SUP_INTEL + help + Enable this to enable Intel PowerClamp idle injection driver. This + enforce idle time which results in more package C-state residency. The + user interface is exposed via generic thermal framework. + endifdrivers/thermal/Makefile +2
-0@@ -18,3 +18,5 @@ obj-$(CONFIG_RCAR_THERMAL) += rcar_thermal.o obj-$(CONFIG_EXYNOS_THERMAL) += exynos_thermal.o obj-$(CONFIG_DB8500_THERMAL) += db8500_thermal.o obj-$(CONFIG_DB8500_CPUFREQ_COOLING) += db8500_cpufreq_cooling.o +obj-$(CONFIG_INTEL_POWERCLAMP) += intel_powerclamp.o +drivers/thermal/intel_powerclamp.c new file +44
-0@@ -0,0 +1,788 @@ +/* +* intel_powerclamp.c - package c-state idle injection +* +* Copyright (c) 2012, Intel Corporation. +* +* Authors: +* Arjan van de Ven <[email protected]> +* Jacob Pan <[email protected]> +* +* This program is free software; you can redistribute it and/or modify it +* under the terms and conditions of the GNU General Public License, +* version 2, as published by the Free Software Foundation. +* +* This program is distributed in the hope it will be useful, but WITHOUT +* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for +* more details. +* +* You should have received a copy of the GNU General Public License along with +* this program; if not, write to the Free Software Foundation, Inc., +* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. +* +* +* TODO: +* 1. better handle wakeup from external interrupts, currently a fixed +* compensation is added to clamping duration when excessive amount +* of wakeups are observed during idle time. the reason is that in +* case of external interrupts without need for ack, clamping down +* cpu in non-irq context does not reduce irq. for majority of the +* cases, clamping down cpu does help reduce irq as well, we should +* be able to differenciate the two cases and give a quantitative +* solution for the irqs that we can control. perhaps based on +* get_cpu_iowait_time_us() +* +* 2. synchronization with other hw blocks +* +* +*/ + +#define pr_fmt (fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/delay.h>
drivers/thermal/intel_powerclamp.c line 54
Quoted 10 lines
drivers/thermal/intel_powerclamp.c new file +10
-0+#include <linux/kthread.h> +#include <linux/freezer.h> +#include <linux/cpu.h> +#include <linux/thermal.h> +#include <linux/slab.h> +#include <linux/tick.h> +#include <linux/debugfs.h> +#include <linux/seq_file.h> +#include <linux/nmi.h> +
drivers/thermal/intel_powerclamp.c: In function ‘clamp_thread’:drivers/thermal/intel_powerclamp.c:435:4: error: implicit declaration of function ‘local_touch_nmi’ [-Werror=implicit-function-declaration]
changing to
#include <asm/nmi.h>
fixes the problem.
thanks,
rui
Zhang Rui
reviewerRe: [PATCH v6 3/3] PM: Introduce Intel PowerClamp Driver
Quoted 117 lines · Zhang Rui
Hi, Jacob,
Quoted 100 lines · Jacob Pan
Intel PowerClamp driver performs synchronized idle injection across all online CPUs. The goal is to maintain a given package level C-state ratio.
Compared to other throttling methods already exist in the kernel, such as ACPI PAD (taking CPUs offline) and clock modulation, this is often more efficient in terms of performance per watt.
Please refer to
Documentation/thermal/intel_powerclamp.txtfor more details.Signed-off-by Arjan van de Ven <[email protected]>Signed-off-by Jacob Pan <[email protected]>--- Documentation/thermal/intel_powerclamp.txt | 307 +++++++++++ drivers/thermal/Kconfig | 10 + drivers/thermal/Makefile | 2 + drivers/thermal/intel_powerclamp.c | 788 ++++++++++++++++++++++++++++ 4 files changed, 1107 insertions(+) create mode 100644 Documentation/thermal/intel_powerclamp.txt create mode 100644 drivers/thermal/intel_powerclamp.cdrivers/thermal/Kconfig +10
-0@@ -122,4 +122,14 @@ config DB8500_CPUFREQ_COOLING bound cpufreq cooling device turns active to set CPU frequency low to cool down the CPU. +config INTEL_POWERCLAMP + tristate "Intel PowerClamp idle injection driver" + depends on THERMAL + depends on X86 + depends on CPU_SUP_INTEL + help + Enable this to enable Intel PowerClamp idle injection driver. This + enforce idle time which results in more package C-state residency. The + user interface is exposed via generic thermal framework. + endifdrivers/thermal/Makefile +2
-0@@ -18,3 +18,5 @@ obj-$(CONFIG_RCAR_THERMAL) += rcar_thermal.o obj-$(CONFIG_EXYNOS_THERMAL) += exynos_thermal.o obj-$(CONFIG_DB8500_THERMAL) += db8500_thermal.o obj-$(CONFIG_DB8500_CPUFREQ_COOLING) += db8500_cpufreq_cooling.o +obj-$(CONFIG_INTEL_POWERCLAMP) += intel_powerclamp.o +drivers/thermal/intel_powerclamp.c new file +44
-0@@ -0,0 +1,788 @@ +/* +* intel_powerclamp.c - package c-state idle injection +* +* Copyright (c) 2012, Intel Corporation. +* +* Authors: +* Arjan van de Ven <[email protected]> +* Jacob Pan <[email protected]> +* +* This program is free software; you can redistribute it and/or modify it +* under the terms and conditions of the GNU General Public License, +* version 2, as published by the Free Software Foundation. +* +* This program is distributed in the hope it will be useful, but WITHOUT +* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for +* more details. +* +* You should have received a copy of the GNU General Public License along with +* this program; if not, write to the Free Software Foundation, Inc., +* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. +* +* +* TODO: +* 1. better handle wakeup from external interrupts, currently a fixed +* compensation is added to clamping duration when excessive amount +* of wakeups are observed during idle time. the reason is that in +* case of external interrupts without need for ack, clamping down +* cpu in non-irq context does not reduce irq. for majority of the +* cases, clamping down cpu does help reduce irq as well, we should +* be able to differenciate the two cases and give a quantitative +* solution for the irqs that we can control. perhaps based on +* get_cpu_iowait_time_us() +* +* 2. synchronization with other hw blocks +* +* +*/ + +#define pr_fmt (fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/delay.h> drivers/thermal/intel_powerclamp.c line 54
Quoted 10 lines
drivers/thermal/intel_powerclamp.c new file +10
-0+#include <linux/kthread.h> +#include <linux/freezer.h> +#include <linux/cpu.h> +#include <linux/thermal.h> +#include <linux/slab.h> +#include <linux/tick.h> +#include <linux/debugfs.h> +#include <linux/seq_file.h> +#include <linux/nmi.h> +
drivers/thermal/intel_powerclamp.c: In function ‘clamp_thread’:drivers/thermal/intel_powerclamp.c:435:4: error: implicit declaration of function ‘local_touch_nmi’ [-Werror=implicit-function-declaration]
Quoted 4 lines
changing to
#include <asm/nmi.h>
fixes the problem.
and this is because I have neither CONFIG_HAVE_NMI_WATCHDOG set nor CONFIG_HARDLOCKUP_DETECTOR set in my configuration. :)
thanks,
rui
Re: [PATCH v6 3/3] PM: Introduce Intel PowerClamp Driver
In reply to Zhang RuiQuoted 9 lines · On Wed, 16 Jan 2013 20:18:49 +0800 Zhang Rui <[email protected]> wrote:
drivers/thermal/intel_powerclamp.c line 54
Quoted 2 lines
drivers/thermal/intel_powerclamp.c new file +2
-0+#include <linux/nmi.h> +
drivers/thermal/intel_powerclamp.c: In function ‘clamp_thread’:drivers/thermal/intel_powerclamp.c:435:4: error: implicit declaration of function ‘local_touch_nmi’ [-Werror=implicit-function-declaration]changing to
#include <asm/nmi.h>
fixes the problem.
good catch. I missed this in my .config tests. I had CONFIG_HARDLOCKUP_DETECTOR on so the problem was not shown. I will send you an update.
Thanks,
Jacob
Quoted 23 lines · Jacob Pan
v6 changes:
- clamp module parameters duration and window size, reword warning messages when input parameters are out of range.We have done some experiment with idle injection on Intel platforms. The idea is to use the increasingly power efficient package level C-states for power capping and passive thermal control.
Documentation is included in the patch to explain the theory of operation, performance implication, calibration, scalability, and user interface. Please refer to the following file for more details.
Documentation/thermal/intel_powerclamp.txtArjan van de Ven created the original idea and driver, I have been refining driver in hope that they can be to be useful beyond a proof of concept.
Jacob Pan (3):
tick: export nohz tick idle symbols for module use x86/nmi: exportlocal_touch_nmi()symbol for modules
PM: Introduce Intel PowerClamp Driver
Quoted 9 lines
Documentation/thermal/intel_powerclamp.txt | 307 +++++++++++ arch/x86/kernel/nmi.c | 1 + drivers/thermal/Kconfig | 10 + drivers/thermal/Makefile | 2 + drivers/thermal/intel_powerclamp.c | 788 ++++++++++++++++++++++++++++ kernel/time/tick-sched.c | 2 + 6 files changed, 1110 insertions(+) create mode 100644 Documentation/thermal/intel_powerclamp.txt create mode 100644 drivers/thermal/intel_powerclamp.c
I'm not seeing any more comments here, so I think this is suitable for v3.9.
Rui, are you going to take it or do you want me to?
Rafael
Signature · 2 lines
I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.