From 8a54cd5bd6ebf009b96ec79510b593f7ba5c0ff3 Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Tue, 6 May 2014 13:01:56 +0200 Subject: PM / hibernate: Documentation: Fix script for unswapping MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit System can have mmaped also character devices (e.g dri devices by X) or deleted files. Running cat on character devices is really bad idea (system can hang) so run cat only on regular files. Also mmaped files can have spaces in filenames. Signed-off-by: Pali Rohár [rjw: Subject] Signed-off-by: Rafael J. Wysocki --- Documentation/power/swsusp.txt | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt index 079160e22bcc..f732a8321e8a 100644 --- a/Documentation/power/swsusp.txt +++ b/Documentation/power/swsusp.txt @@ -220,7 +220,10 @@ Q: After resuming, system is paging heavily, leading to very bad interactivity. A: Try running -cat `cat /proc/[0-9]*/maps | grep / | sed 's:.* /:/:' | sort -u` > /dev/null +cat /proc/[0-9]*/maps | grep / | sed 's:.* /:/:' | sort -u | while read file +do + test -f "$file" && cat "$file" > /dev/null +done after resume. swapoff -a; swapon -a may also be useful. -- cgit v1.2.3 From f71495f3f0c5f0801823d1235b271a4a415d3df8 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 16 May 2014 02:47:37 +0200 Subject: PM / sleep: Update device PM documentation to cover direct_complete Update the device PM documentation in devices.txt and runtime_pm.txt to reflect the changes in the system suspend and resume handling related to the introduction of the new power.direct_complete flag. Signed-off-by: Rafael J. Wysocki Acked-by: Alan Stern --- Documentation/power/devices.txt | 34 ++++++++++++++++++++++++++++++---- Documentation/power/runtime_pm.txt | 17 +++++++++++++++++ 2 files changed, 47 insertions(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt index 47d46dff70f7..d172bce0fd49 100644 --- a/Documentation/power/devices.txt +++ b/Documentation/power/devices.txt @@ -2,6 +2,7 @@ Device Power Management Copyright (c) 2010-2011 Rafael J. Wysocki , Novell Inc. Copyright (c) 2010 Alan Stern +Copyright (c) 2014 Intel Corp., Rafael J. Wysocki Most of the code in Linux is device drivers, so most of the Linux power @@ -326,6 +327,20 @@ the phases are: driver in some way for the upcoming system power transition, but it should not put the device into a low-power state. + For devices supporting runtime power management, the return value of the + prepare callback can be used to indicate to the PM core that it may + safely leave the device in runtime suspend (if runtime-suspended + already), provided that all of the device's descendants are also left in + runtime suspend. Namely, if the prepare callback returns a positive + number and that happens for all of the descendants of the device too, + and all of them (including the device itself) are runtime-suspended, the + PM core will skip the suspend, suspend_late and suspend_noirq suspend + phases as well as the resume_noirq, resume_early and resume phases of + the following system resume for all of these devices. In that case, + the complete callback will be called directly after the prepare callback + and is entirely responsible for bringing the device back to the + functional state as appropriate. + 2. The suspend methods should quiesce the device to stop it from performing I/O. They also may save the device registers and put it into the appropriate low-power state, depending on the bus type the device is on, @@ -400,12 +415,23 @@ When resuming from freeze, standby or memory sleep, the phases are: the resume callbacks occur; it's not necessary to wait until the complete phase. + Moreover, if the preceding prepare callback returned a positive number, + the device may have been left in runtime suspend throughout the whole + system suspend and resume (the suspend, suspend_late, suspend_noirq + phases of system suspend and the resume_noirq, resume_early, resume + phases of system resume may have been skipped for it). In that case, + the complete callback is entirely responsible for bringing the device + back to the functional state after system suspend if necessary. [For + example, it may need to queue up a runtime resume request for the device + for this purpose.] To check if that is the case, the complete callback + can consult the device's power.direct_complete flag. Namely, if that + flag is set when the complete callback is being run, it has been called + directly after the preceding prepare and special action may be required + to make the device work correctly afterward. + At the end of these phases, drivers should be as functional as they were before suspending: I/O can be performed using DMA and IRQs, and the relevant clocks are -gated on. Even if the device was in a low-power state before the system sleep -because of runtime power management, afterwards it should be back in its -full-power state. There are multiple reasons why it's best to do this; they are -discussed in more detail in Documentation/power/runtime_pm.txt. +gated on. However, the details here may again be platform-specific. For example, some systems support multiple "run" states, and the mode in effect at diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt index 5f96daf8566a..e1bee8a4aaac 100644 --- a/Documentation/power/runtime_pm.txt +++ b/Documentation/power/runtime_pm.txt @@ -2,6 +2,7 @@ Runtime Power Management Framework for I/O Devices (C) 2009-2011 Rafael J. Wysocki , Novell Inc. (C) 2010 Alan Stern +(C) 2014 Intel Corp., Rafael J. Wysocki 1. Introduction @@ -444,6 +445,10 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: bool pm_runtime_status_suspended(struct device *dev); - return true if the device's runtime PM status is 'suspended' + bool pm_runtime_suspended_if_enabled(struct device *dev); + - return true if the device's runtime PM status is 'suspended' and its + 'power.disable_depth' field is equal to 1 + void pm_runtime_allow(struct device *dev); - set the power.runtime_auto flag for the device and decrease its usage counter (used by the /sys/devices/.../power/control interface to @@ -644,6 +649,18 @@ place (in particular, if the system is not waking up from hibernation), it may be more efficient to leave the devices that had been suspended before the system suspend began in the suspended state. +To this end, the PM core provides a mechanism allowing some coordination between +different levels of device hierarchy. Namely, if a system suspend .prepare() +callback returns a positive number for a device, that indicates to the PM core +that the device appears to be runtime-suspended and its state is fine, so it +may be left in runtime suspend provided that all of its descendants are also +left in runtime suspend. If that happens, the PM core will not execute any +system suspend and resume callbacks for all of those devices, except for the +complete callback, which is then entirely responsible for handling the device +as appropriate. This only applies to system suspend transitions that are not +related to hibernation (see Documentation/power/devices.txt for more +information). + The PM core does its best to reduce the probability of race conditions between the runtime PM and system suspend/resume (and hibernation) callbacks by carrying out the following operations: -- cgit v1.2.3 From 0399d4db3edf5c58b6ec7f672f089f5085e49ed5 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 26 May 2014 13:40:59 +0200 Subject: PM / sleep: Introduce command line argument for sleep state enumeration On some systems the platform doesn't support neither PM_SUSPEND_MEM nor PM_SUSPEND_STANDBY, so PM_SUSPEND_FREEZE is the only available system sleep state. However, some user space frameworks only use the "mem" and (sometimes) "standby" sleep state labels, so the users of those systems need to modify user space in order to be able to use system suspend at all and that is not always possible. For this reason, add a new kernel command line argument, relative_sleep_states, allowing the users of those systems to change the way in which the kernel assigns labels to system sleep states. Namely, for relative_sleep_states=1, the "mem", "standby" and "freeze" labels will enumerate the available system sleem states from the deepest to the shallowest, respectively, so that "mem" is always present in /sys/power/state and the other state strings may or may not be presend depending on what is supported by the platform. Update system sleep states documentation to reflect this change. Signed-off-by: Rafael J. Wysocki --- Documentation/ABI/testing/sysfs-power | 29 ++++++++---- Documentation/kernel-parameters.txt | 7 +++ Documentation/power/states.txt | 87 ++++++++++++++++++++++------------- kernel/power/main.c | 12 ++--- kernel/power/suspend.c | 32 ++++++++++++- 5 files changed, 119 insertions(+), 48 deletions(-) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index 64c9276e9421..f4551816329e 100644 --- a/Documentation/ABI/testing/sysfs-power +++ b/Documentation/ABI/testing/sysfs-power @@ -7,19 +7,30 @@ Description: subsystem. What: /sys/power/state -Date: August 2006 +Date: May 2014 Contact: Rafael J. Wysocki Description: - The /sys/power/state file controls the system power state. - Reading from this file returns what states are supported, - which is hard-coded to 'freeze' (Low-Power Idle), 'standby' - (Power-On Suspend), 'mem' (Suspend-to-RAM), and 'disk' - (Suspend-to-Disk). + The /sys/power/state file controls system sleep states. + Reading from this file returns the available sleep state + labels, which may be "mem", "standby", "freeze" and "disk" + (hibernation). The meanings of the first three labels depend on + the relative_sleep_states command line argument as follows: + 1) relative_sleep_states = 1 + "mem", "standby", "freeze" represent non-hibernation sleep + states from the deepest ("mem", always present) to the + shallowest ("freeze"). "standby" and "freeze" may or may + not be present depending on the capabilities of the + platform. "freeze" can only be present if "standby" is + present. + 2) relative_sleep_states = 0 (default) + "mem" - "suspend-to-RAM", present if supported. + "standby" - "power-on suspend", present if supported. + "freeze" - "suspend-to-idle", always present. Writing to this file one of these strings causes the system to - transition into that state. Please see the file - Documentation/power/states.txt for a description of each of - these states. + transition into the corresponding state, if available. See + Documentation/power/states.txt for a description of what + "suspend-to-RAM", "power-on suspend" and "suspend-to-idle" mean. What: /sys/power/disk Date: September 2006 diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 43842177b771..e19a88b63eeb 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2889,6 +2889,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/cgroups/cpusets.txt. + relative_sleep_states= + [SUSPEND] Use sleep state labeling where the deepest + state available other than hibernation is always "mem". + Format: { "0" | "1" } + 0 -- Traditional sleep state labels. + 1 -- Relative sleep state labels. + reserve= [KNL,BUGS] Force the kernel to ignore some iomem area reservetop= [X86-32] diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt index 442d43df9b25..50f3ef9177c1 100644 --- a/Documentation/power/states.txt +++ b/Documentation/power/states.txt @@ -1,62 +1,87 @@ +System Power Management Sleep States -System Power Management States +(C) 2014 Intel Corp., Rafael J. Wysocki +The kernel supports up to four system sleep states generically, although three +of them depend on the platform support code to implement the low-level details +for each state. -The kernel supports four power management states generically, though -one is generic and the other three are dependent on platform support -code to implement the low-level details for each state. -This file describes each state, what they are -commonly called, what ACPI state they map to, and what string to write -to /sys/power/state to enter that state +The states are represented by strings that can be read or written to the +/sys/power/state file. Those strings may be "mem", "standby", "freeze" and +"disk", where the last one always represents hibernation (Suspend-To-Disk) and +the meaning of the remaining ones depends on the relative_sleep_states command +line argument. -state: Freeze / Low-Power Idle +For relative_sleep_states=1, the strings "mem", "standby" and "freeze" label the +available non-hibernation sleep states from the deepest to the shallowest, +respectively. In that case, "mem" is always present in /sys/power/state, +because there is at least one non-hibernation sleep state in every system. If +the given system supports two non-hibernation sleep states, "standby" is present +in /sys/power/state in addition to "mem". If the system supports three +non-hibernation sleep states, "freeze" will be present in /sys/power/state in +addition to "mem" and "standby". + +For relative_sleep_states=0, which is the default, the following descriptions +apply. + +state: Suspend-To-Idle ACPI state: S0 -String: "freeze" +Label: "freeze" -This state is a generic, pure software, light-weight, low-power state. -It allows more energy to be saved relative to idle by freezing user +This state is a generic, pure software, light-weight, system sleep state. +It allows more energy to be saved relative to runtime idle by freezing user space and putting all I/O devices into low-power states (possibly lower-power than available at run time), such that the processors can spend more time in their idle states. -This state can be used for platforms without Standby/Suspend-to-RAM + +This state can be used for platforms without Power-On Suspend/Suspend-to-RAM support, or it can be used in addition to Suspend-to-RAM (memory sleep) -to provide reduced resume latency. +to provide reduced resume latency. It is always supported. State: Standby / Power-On Suspend ACPI State: S1 -String: "standby" +Label: "standby" -This state offers minimal, though real, power savings, while providing -a very low-latency transition back to a working system. No operating -state is lost (the CPU retains power), so the system easily starts up +This state, if supported, offers moderate, though real, power savings, while +providing a relatively low-latency transition back to a working system. No +operating state is lost (the CPU retains power), so the system easily starts up again where it left off. -We try to put devices in a low-power state equivalent to D1, which -also offers low power savings, but low resume latency. Not all devices -support D1, and those that don't are left on. +In addition to freezing user space and putting all I/O devices into low-power +states, which is done for Suspend-To-Idle too, nonboot CPUs are taken offline +and all low-level system functions are suspended during transitions into this +state. For this reason, it should allow more energy to be saved relative to +Suspend-To-Idle, but the resume latency will generally be greater than for that +state. State: Suspend-to-RAM ACPI State: S3 -String: "mem" +Label: "mem" -This state offers significant power savings as everything in the -system is put into a low-power state, except for memory, which is -placed in self-refresh mode to retain its contents. +This state, if supported, offers significant power savings as everything in the +system is put into a low-power state, except for memory, which should be placed +into the self-refresh mode to retain its contents. All of the steps carried out +when entering Power-On Suspend are also carried out during transitions to STR. +Additional operations may take place depending on the platform capabilities. In +particular, on ACPI systems the kernel passes control to the BIOS (platform +firmware) as the last step during STR transitions and that usually results in +powering down some more low-level components that aren't directly controlled by +the kernel. -System and device state is saved and kept in memory. All devices are -suspended and put into D3. In many cases, all peripheral buses lose -power when entering STR, so devices must be able to handle the -transition back to the On state. +System and device state is saved and kept in memory. All devices are suspended +and put into low-power states. In many cases, all peripheral buses lose power +when entering STR, so devices must be able to handle the transition back to the +"on" state. -For at least ACPI, STR requires some minimal boot-strapping code to -resume the system from STR. This may be true on other platforms. +For at least ACPI, STR requires some minimal boot-strapping code to resume the +system from it. This may be the case on other platforms too. State: Suspend-to-disk ACPI State: S4 -String: "disk" +Label: "disk" This state offers the greatest power savings, and can be used even in the absence of low-level platform support for power management. This diff --git a/kernel/power/main.c b/kernel/power/main.c index 9f51f0ab3d86..573410d6647e 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -279,14 +279,14 @@ static inline void pm_print_times_init(void) {} struct kobject *power_kobj; /** - * state - control system power state. + * state - control system sleep states. * - * show() returns what states are supported, which is hard-coded to - * 'freeze' (Low-Power Idle), 'standby' (Power-On Suspend), - * 'mem' (Suspend-to-RAM), and 'disk' (Suspend-to-Disk). + * show() returns available sleep state labels, which may be "mem", "standby", + * "freeze" and "disk" (hibernation). See Documentation/power/states.txt for a + * description of what they mean. * - * store() accepts one of those strings, translates it into the - * proper enumerated value, and initiates a suspend transition. + * store() accepts one of those strings, translates it into the proper + * enumerated value, and initiates a suspend transition. */ static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 00aca60904b0..338a6f147974 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -78,6 +78,26 @@ static bool valid_state(suspend_state_t state) return suspend_ops && suspend_ops->valid && suspend_ops->valid(state); } +/* + * If this is set, the "mem" label always corresponds to the deepest sleep state + * available, the "standby" label corresponds to the second deepest sleep state + * available (if any), and the "freeze" label corresponds to the remaining + * available sleep state (if there is one). + */ +static bool relative_states; + +static int __init sleep_states_setup(char *str) +{ + relative_states = !strncmp(str, "1", 1); + if (relative_states) { + pm_states[PM_SUSPEND_MEM].state = PM_SUSPEND_FREEZE; + pm_states[PM_SUSPEND_FREEZE].state = 0; + } + return 1; +} + +__setup("relative_sleep_states=", sleep_states_setup); + /** * suspend_set_ops - Set the global suspend method table. * @ops: Suspend operations to use. @@ -85,12 +105,20 @@ static bool valid_state(suspend_state_t state) void suspend_set_ops(const struct platform_suspend_ops *ops) { suspend_state_t i; + int j = PM_SUSPEND_MAX - 1; lock_system_sleep(); suspend_ops = ops; - for (i = PM_SUSPEND_STANDBY; i <= PM_SUSPEND_MEM; i++) - pm_states[i].state = valid_state(i) ? i : 0; + for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--) + if (valid_state(i)) + pm_states[j--].state = i; + else if (!relative_states) + pm_states[j--].state = 0; + + pm_states[j--].state = PM_SUSPEND_FREEZE; + while (j >= PM_SUSPEND_MIN) + pm_states[j--].state = 0; unlock_system_sleep(); } -- cgit v1.2.3