diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-wakeup | 76 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-power | 9 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-power | 106 | ||||
| -rw-r--r-- | Documentation/cpu-freq/core.txt | 16 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/opp/opp.txt | 4 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/opp/qcom-nvmem-cpufreq.txt (renamed from Documentation/devicetree/bindings/opp/kryo-cpufreq.txt) | 127 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/opp/qcom-opp.txt | 19 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/opp/sun50i-nvmem-cpufreq.txt | 167 | ||||
| -rw-r--r-- | Documentation/power/opp.rst | 2 | ||||
| -rw-r--r-- | Documentation/power/pm_qos_interface.rst | 5 | ||||
| -rw-r--r-- | Documentation/virtual/guest-halt-polling.txt | 78 |
11 files changed, 585 insertions, 24 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-wakeup b/Documentation/ABI/testing/sysfs-class-wakeup new file mode 100644 index 000000000000..754aab8b6dcd --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-wakeup @@ -0,0 +1,76 @@ +What: /sys/class/wakeup/ +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + The /sys/class/wakeup/ directory contains pointers to all + wakeup sources in the kernel at that moment in time. + +What: /sys/class/wakeup/.../name +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the name of the wakeup source. + +What: /sys/class/wakeup/.../active_count +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the number of times the wakeup source was + activated. + +What: /sys/class/wakeup/.../event_count +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the number of signaled wakeup events + associated with the wakeup source. + +What: /sys/class/wakeup/.../wakeup_count +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the number of times the wakeup source might + abort suspend. + +What: /sys/class/wakeup/.../expire_count +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the number of times the wakeup source's + timeout has expired. + +What: /sys/class/wakeup/.../active_time_ms +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the amount of time the wakeup source has + been continuously active, in milliseconds. If the wakeup + source is not active, this file contains '0'. + +What: /sys/class/wakeup/.../total_time_ms +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the total amount of time this wakeup source + has been active, in milliseconds. + +What: /sys/class/wakeup/.../max_time_ms +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the maximum amount of time this wakeup + source has been continuously active, in milliseconds. + +What: /sys/class/wakeup/.../last_change_ms +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + This file contains the monotonic clock time when the wakeup + source was touched last time, in milliseconds. + +What: /sys/class/wakeup/.../prevent_suspend_time_ms +Date: June 2019 +Contact: Tri Vo <trong@android.com> +Description: + The file contains the total amount of time this wakeup source + has been preventing autosleep, in milliseconds. diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power index 80a00f7b6667..1763e64dd152 100644 --- a/Documentation/ABI/testing/sysfs-devices-power +++ b/Documentation/ABI/testing/sysfs-devices-power @@ -260,3 +260,12 @@ Description: This attribute has no effect on system-wide suspend/resume and hibernation. + +What: /sys/devices/.../power/runtime_status +Date: April 2010 +Contact: Rafael J. Wysocki <rjw@rjwysocki.net> +Description: + The /sys/devices/.../power/runtime_status attribute contains + the current runtime PM status of the device, which may be + "suspended", "suspending", "resuming", "active", "error" (fatal + error), or "unsupported" (runtime PM is disabled). diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index 3c5130355011..6f87b9dd384b 100644 --- a/Documentation/ABI/testing/sysfs-power +++ b/Documentation/ABI/testing/sysfs-power @@ -301,3 +301,109 @@ Description: Using this sysfs file will override any values that were set using the kernel command line for disk offset. + +What: /sys/power/suspend_stats +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats directory contains suspend related + statistics. + +What: /sys/power/suspend_stats/success +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/success file contains the number + of times entering system sleep state succeeded. + +What: /sys/power/suspend_stats/fail +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/fail file contains the number + of times entering system sleep state failed. + +What: /sys/power/suspend_stats/failed_freeze +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_freeze file contains the + number of times freezing processes failed. + +What: /sys/power/suspend_stats/failed_prepare +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_prepare file contains the + number of times preparing all non-sysdev devices for + a system PM transition failed. + +What: /sys/power/suspend_stats/failed_resume +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_resume file contains the + number of times executing "resume" callbacks of + non-sysdev devices failed. + +What: /sys/power/suspend_stats/failed_resume_early +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_resume_early file contains + the number of times executing "early resume" callbacks + of devices failed. + +What: /sys/power/suspend_stats/failed_resume_noirq +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_resume_noirq file contains + the number of times executing "noirq resume" callbacks + of devices failed. + +What: /sys/power/suspend_stats/failed_suspend +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_suspend file contains + the number of times executing "suspend" callbacks + of all non-sysdev devices failed. + +What: /sys/power/suspend_stats/failed_suspend_late +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_suspend_late file contains + the number of times executing "late suspend" callbacks + of all devices failed. + +What: /sys/power/suspend_stats/failed_suspend_noirq +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/failed_suspend_noirq file contains + the number of times executing "noirq suspend" callbacks + of all devices failed. + +What: /sys/power/suspend_stats/last_failed_dev +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/last_failed_dev file contains + the last device for which a suspend/resume callback failed. + +What: /sys/power/suspend_stats/last_failed_errno +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/last_failed_errno file contains + the errno of the last failed attempt at entering + system sleep state. + +What: /sys/power/suspend_stats/last_failed_step +Date: July 2019 +Contact: Kalesh Singh <kaleshsingh96@gmail.com> +Description: + The /sys/power/suspend_stats/last_failed_step file contains + the last failed step in the suspend/resume path. diff --git a/Documentation/cpu-freq/core.txt b/Documentation/cpu-freq/core.txt index 55193e680250..ed577d9c154b 100644 --- a/Documentation/cpu-freq/core.txt +++ b/Documentation/cpu-freq/core.txt @@ -57,19 +57,11 @@ transition notifiers. 2.1 CPUFreq policy notifiers ---------------------------- -These are notified when a new policy is intended to be set. Each -CPUFreq policy notifier is called twice for a policy transition: +These are notified when a new policy is created or removed. -1.) During CPUFREQ_ADJUST all CPUFreq notifiers may change the limit if - they see a need for this - may it be thermal considerations or - hardware limitations. - -2.) And during CPUFREQ_NOTIFY all notifiers are informed of the new policy - - if two hardware drivers failed to agree on a new policy before this - stage, the incompatible hardware shall be shut down, and the user - informed of this. - -The phase is specified in the second argument to the notifier. +The phase is specified in the second argument to the notifier. The phase is +CPUFREQ_CREATE_POLICY when the policy is first created and it is +CPUFREQ_REMOVE_POLICY when the policy is removed. The third argument, a void *pointer, points to a struct cpufreq_policy consisting of several values, including min, max (the lower and upper diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt index 76b6c79604a5..68592271461f 100644 --- a/Documentation/devicetree/bindings/opp/opp.txt +++ b/Documentation/devicetree/bindings/opp/opp.txt @@ -140,8 +140,8 @@ Optional properties: frequency for a short duration of time limited by the device's power, current and thermal limits. -- opp-suspend: Marks the OPP to be used during device suspend. Only one OPP in - the table should have this. +- opp-suspend: Marks the OPP to be used during device suspend. If multiple OPPs + in the table have this, the OPP with highest opp-hz will be used. - opp-supported-hw: This enables us to select only a subset of OPPs from the larger OPP table, based on what version of the hardware we are running on. We diff --git a/Documentation/devicetree/bindings/opp/kryo-cpufreq.txt b/Documentation/devicetree/bindings/opp/qcom-nvmem-cpufreq.txt index c2127b96805a..4751029b9b74 100644 --- a/Documentation/devicetree/bindings/opp/kryo-cpufreq.txt +++ b/Documentation/devicetree/bindings/opp/qcom-nvmem-cpufreq.txt @@ -1,25 +1,38 @@ -Qualcomm Technologies, Inc. KRYO CPUFreq and OPP bindings +Qualcomm Technologies, Inc. NVMEM CPUFreq and OPP bindings =================================== -In Certain Qualcomm Technologies, Inc. SoCs like apq8096 and msm8996 -that have KRYO processors, the CPU ferequencies subset and voltage value -of each OPP varies based on the silicon variant in use. +In Certain Qualcomm Technologies, Inc. SoCs like apq8096 and msm8996, +the CPU frequencies subset and voltage value of each OPP varies based on +the silicon variant in use. Qualcomm Technologies, Inc. Process Voltage Scaling Tables defines the voltage and frequency value based on the msm-id in SMEM and speedbin blown in the efuse combination. -The qcom-cpufreq-kryo driver reads the msm-id and efuse value from the SoC +The qcom-cpufreq-nvmem driver reads the msm-id and efuse value from the SoC to provide the OPP framework with required information (existing HW bitmap). This is used to determine the voltage and frequency value for each OPP of operating-points-v2 table when it is parsed by the OPP framework. Required properties: -------------------- -In 'cpus' nodes: +In 'cpu' nodes: - operating-points-v2: Phandle to the operating-points-v2 table to use. In 'operating-points-v2' table: - compatible: Should be - 'operating-points-v2-kryo-cpu' for apq8096 and msm8996. + +Optional properties: +-------------------- +In 'cpu' nodes: +- power-domains: A phandle pointing to the PM domain specifier which provides + the performance states available for active state management. + Please refer to the power-domains bindings + Documentation/devicetree/bindings/power/power_domain.txt + and also examples below. +- power-domain-names: Should be + - 'cpr' for qcs404. + +In 'operating-points-v2' table: - nvmem-cells: A phandle pointing to a nvmem-cells node representing the efuse registers that has information about the speedbin that is used to select the right frequency/voltage @@ -678,3 +691,105 @@ soc { }; }; }; + +Example 2: +--------- + + cpus { + #address-cells = <1>; + #size-cells = <0>; + + CPU0: cpu@100 { + device_type = "cpu"; + compatible = "arm,cortex-a53"; + reg = <0x100>; + .... + clocks = <&apcs_glb>; + operating-points-v2 = <&cpu_opp_table>; + power-domains = <&cpr>; + power-domain-names = "cpr"; + }; + + CPU1: cpu@101 { + device_type = "cpu"; + compatible = "arm,cortex-a53"; + reg = <0x101>; + .... + clocks = <&apcs_glb>; + operating-points-v2 = <&cpu_opp_table>; + power-domains = <&cpr>; + power-domain-names = "cpr"; + }; + + CPU2: cpu@102 { + device_type = "cpu"; + compatible = "arm,cortex-a53"; + reg = <0x102>; + .... + clocks = <&apcs_glb>; + operating-points-v2 = <&cpu_opp_table>; + power-domains = <&cpr>; + power-domain-names = "cpr"; + }; + + CPU3: cpu@103 { + device_type = "cpu"; + compatible = "arm,cortex-a53"; + reg = <0x103>; + .... + clocks = <&apcs_glb>; + operating-points-v2 = <&cpu_opp_table>; + power-domains = <&cpr>; + power-domain-names = "cpr"; + }; + }; + + cpu_opp_table: cpu-opp-table { + compatible = "operating-points-v2-kryo-cpu"; + opp-shared; + + opp-1094400000 { + opp-hz = /bits/ 64 <1094400000>; + required-opps = <&cpr_opp1>; + }; + opp-1248000000 { + opp-hz = /bits/ 64 <1248000000>; + required-opps = <&cpr_opp2>; + }; + opp-1401600000 { + opp-hz = /bits/ 64 <1401600000>; + required-opps = <&cpr_opp3>; + }; + }; + + cpr_opp_table: cpr-opp-table { + compatible = "operating-points-v2-qcom-level"; + + cpr_opp1: opp1 { + opp-level = <1>; + qcom,opp-fuse-level = <1>; + }; + cpr_opp2: opp2 { + opp-level = <2>; + qcom,opp-fuse-level = <2>; + }; + cpr_opp3: opp3 { + opp-level = <3>; + qcom,opp-fuse-level = <3>; + }; + }; + +.... + +soc { +.... + cpr: power-controller@b018000 { + compatible = "qcom,qcs404-cpr", "qcom,cpr"; + reg = <0x0b018000 0x1000>; + .... + vdd-apc-supply = <&pms405_s3>; + #power-domain-cells = <0>; + operating-points-v2 = <&cpr_opp_table>; + .... + }; +}; diff --git a/Documentation/devicetree/bindings/opp/qcom-opp.txt b/Documentation/devicetree/bindings/opp/qcom-opp.txt new file mode 100644 index 000000000000..32eb0793c7e6 --- /dev/null +++ b/Documentation/devicetree/bindings/opp/qcom-opp.txt @@ -0,0 +1,19 @@ +Qualcomm OPP bindings to describe OPP nodes + +The bindings are based on top of the operating-points-v2 bindings +described in Documentation/devicetree/bindings/opp/opp.txt +Additional properties are described below. + +* OPP Table Node + +Required properties: +- compatible: Allow OPPs to express their compatibility. It should be: + "operating-points-v2-qcom-level" + +* OPP Node + +Required properties: +- qcom,opp-fuse-level: A positive value representing the fuse corner/level + associated with this OPP node. Sometimes several corners/levels shares + a certain fuse corner/level. A fuse corner/level contains e.g. ref uV, + min uV, and max uV. diff --git a/Documentation/devicetree/bindings/opp/sun50i-nvmem-cpufreq.txt b/Documentation/devicetree/bindings/opp/sun50i-nvmem-cpufreq.txt new file mode 100644 index 000000000000..7deae57a587b --- /dev/null +++ b/Documentation/devicetree/bindings/opp/sun50i-nvmem-cpufreq.txt @@ -0,0 +1,167 @@ +Allwinner Technologies, Inc. NVMEM CPUFreq and OPP bindings +=================================== + +For some SoCs, the CPU frequency subset and voltage value of each OPP +varies based on the silicon variant in use. Allwinner Process Voltage +Scaling Tables defines the voltage and frequency value based on the +speedbin blown in the efuse combination. The sun50i-cpufreq-nvmem driver +reads the efuse value from the SoC to provide the OPP framework with +required information. + +Required properties: +-------------------- +In 'cpus' nodes: +- operating-points-v2: Phandle to the operating-points-v2 table to use. + +In 'operating-points-v2' table: +- compatible: Should be + - 'allwinner,sun50i-h6-operating-points'. +- nvmem-cells: A phandle pointing to a nvmem-cells node representing the + efuse registers that has information about the speedbin + that is used to select the right frequency/voltage value + pair. Please refer the for nvmem-cells bindings + Documentation/devicetree/bindings/nvmem/nvmem.txt and + also examples below. + +In every OPP node: +- opp-microvolt-<name>: Voltage in micro Volts. + At runtime, the platform can pick a <name> and + matching opp-microvolt-<name> property. + [See: opp.txt] + HW: <name>: + sun50i-h6 speed0 speed1 speed2 + +Example 1: +--------- + + cpus { + #address-cells = <1>; + #size-cells = <0>; + + cpu0: cpu@0 { + compatible = "arm,cortex-a53"; + device_type = "cpu"; + reg = <0>; + enable-method = "psci"; + clocks = <&ccu CLK_CPUX>; + clock-latency-ns = <244144>; /* 8 32k periods */ + operating-points-v2 = <&cpu_opp_table>; + #cooling-cells = <2>; + }; + + cpu1: cpu@1 { + compatible = "arm,cortex-a53"; + device_type = "cpu"; + reg = <1>; + enable-method = "psci"; + clocks = <&ccu CLK_CPUX>; + clock-latency-ns = <244144>; /* 8 32k periods */ + operating-points-v2 = <&cpu_opp_table>; + #cooling-cells = <2>; + }; + + cpu2: cpu@2 { + compatible = "arm,cortex-a53"; + device_type = "cpu"; + reg = <2>; + enable-method = "psci"; + clocks = <&ccu CLK_CPUX>; + clock-latency-ns = <244144>; /* 8 32k periods */ + operating-points-v2 = <&cpu_opp_table>; + #cooling-cells = <2>; + }; + + cpu3: cpu@3 { + compatible = "arm,cortex-a53"; + device_type = "cpu"; + reg = <3>; + enable-method = "psci"; + clocks = <&ccu CLK_CPUX>; + clock-latency-ns = <244144>; /* 8 32k periods */ + operating-points-v2 = <&cpu_opp_table>; + #cooling-cells = <2>; + }; + }; + + cpu_opp_table: opp_table { + compatible = "allwinner,sun50i-h6-operating-points"; + nvmem-cells = <&speedbin_efuse>; + opp-shared; + + opp@480000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <480000000>; + + opp-microvolt-speed0 = <880000>; + opp-microvolt-speed1 = <820000>; + opp-microvolt-speed2 = <800000>; + }; + + opp@720000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <720000000>; + + opp-microvolt-speed0 = <880000>; + opp-microvolt-speed1 = <820000>; + opp-microvolt-speed2 = <800000>; + }; + + opp@816000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <816000000>; + + opp-microvolt-speed0 = <880000>; + opp-microvolt-speed1 = <820000>; + opp-microvolt-speed2 = <800000>; + }; + + opp@888000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <888000000>; + + opp-microvolt-speed0 = <940000>; + opp-microvolt-speed1 = <820000>; + opp-microvolt-speed2 = <800000>; + }; + + opp@1080000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <1080000000>; + + opp-microvolt-speed0 = <1060000>; + opp-microvolt-speed1 = <880000>; + opp-microvolt-speed2 = <840000>; + }; + + opp@1320000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <1320000000>; + + opp-microvolt-speed0 = <1160000>; + opp-microvolt-speed1 = <940000>; + opp-microvolt-speed2 = <900000>; + }; + + opp@1488000000 { + clock-latency-ns = <244144>; /* 8 32k periods */ + opp-hz = /bits/ 64 <1488000000>; + + opp-microvolt-speed0 = <1160000>; + opp-microvolt-speed1 = <1000000>; + opp-microvolt-speed2 = <960000>; + }; + }; +.... +soc { +.... + sid: sid@3006000 { + compatible = "allwinner,sun50i-h6-sid"; + reg = <0x03006000 0x400>; + #address-cells = <1>; + #size-cells = <1>; + .... + speedbin_efuse: speed@1c { + reg = <0x1c 4>; + }; + }; +}; diff --git a/Documentation/power/opp.rst b/Documentation/power/opp.rst index b3cf1def9dee..209c7613f5a4 100644 --- a/Documentation/power/opp.rst +++ b/Documentation/power/opp.rst @@ -46,7 +46,7 @@ We can represent these as three OPPs as the following {Hz, uV} tuples: ---------------------------------------- OPP library provides a set of helper functions to organize and query the OPP -information. The library is located in drivers/base/power/opp.c and the header +information. The library is located in drivers/opp/ directory and the header is located in include/linux/pm_opp.h. OPP library can be enabled by enabling CONFIG_PM_OPP from power management menuconfig menu. OPP library depends on CONFIG_PM as certain SoCs such as Texas Instrument's OMAP framework allows to diff --git a/Documentation/power/pm_qos_interface.rst b/Documentation/power/pm_qos_interface.rst index 69921f072ce1..3097694fba69 100644 --- a/Documentation/power/pm_qos_interface.rst +++ b/Documentation/power/pm_qos_interface.rst @@ -7,8 +7,7 @@ performance expectations by drivers, subsystems and user space applications on one of the parameters. Two different PM QoS frameworks are available: -1. PM QoS classes for cpu_dma_latency, network_latency, network_throughput, -memory_bandwidth. +1. PM QoS classes for cpu_dma_latency 2. the per-device PM QoS framework provides the API to manage the per-device latency constraints and PM QoS flags. @@ -79,7 +78,7 @@ cleanup of a process, the interface requires the process to register its parameter requests in the following way: To register the default pm_qos target for the specific parameter, the process -must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] +must open /dev/cpu_dma_latency As long as the device node is held open that process has a registered request on the parameter. diff --git a/Documentation/virtual/guest-halt-polling.txt b/Documentation/virtual/guest-halt-polling.txt new file mode 100644 index 000000000000..b3a2a294532d --- /dev/null +++ b/Documentation/virtual/guest-halt-polling.txt @@ -0,0 +1,78 @@ +Guest halt polling +================== + +The cpuidle_haltpoll driver, with the haltpoll governor, allows +the guest vcpus to poll for a specified amount of time before +halting. +This provides the following benefits to host side polling: + + 1) The POLL flag is set while polling is performed, which allows + a remote vCPU to avoid sending an IPI (and the associated + cost of handling the IPI) when performing a wakeup. + + 2) The VM-exit cost can be avoided. + +The downside of guest side polling is that polling is performed +even with other runnable tasks in the host. + +The basic logic as follows: A global value, guest_halt_poll_ns, +is configured by the user, indicating the maximum amount of +time polling is allowed. This value is fixed. + +Each vcpu has an adjustable guest_halt_poll_ns +("per-cpu guest_halt_poll_ns"), which is adjusted by the algorithm +in response to events (explained below). + +Module Parameters +================= + +The haltpoll governor has 5 tunable module parameters: + +1) guest_halt_poll_ns: +Maximum amount of time, in nanoseconds, that polling is +performed before halting. + +Default: 200000 + +2) guest_halt_poll_shrink: +Division factor used to shrink per-cpu guest_halt_poll_ns when +wakeup event occurs after the global guest_halt_poll_ns. + +Default: 2 + +3) guest_halt_poll_grow: +Multiplication factor used to grow per-cpu guest_halt_poll_ns +when event occurs after per-cpu guest_halt_poll_ns +but before global guest_halt_poll_ns. + +Default: 2 + +4) guest_halt_poll_grow_start: +The per-cpu guest_halt_poll_ns eventually reaches zero +in case of an idle system. This value sets the initial +per-cpu guest_halt_poll_ns when growing. This can +be increased from 10000, to avoid misses during the initial +growth stage: + +10k, 20k, 40k, ... (example assumes guest_halt_poll_grow=2). + +Default: 50000 + +5) guest_halt_poll_allow_shrink: + +Bool parameter which allows shrinking. Set to N +to avoid it (per-cpu guest_halt_poll_ns will remain +high once achieves global guest_halt_poll_ns value). + +Default: Y + +The module parameters can be set from the debugfs files in: + + /sys/module/haltpoll/parameters/ + +Further Notes +============= + +- Care should be taken when setting the guest_halt_poll_ns parameter as a +large value has the potential to drive the cpu usage to 100% on a machine which +would be almost entirely idle otherwise. |
