Re: [PATCH] PM: trace events for suspend/resume

["Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>]

On 05/22/2014 05:31 AM, Rafael J. Wysocki wrote:
> On Monday, May 19, 2014 04:02:26 PM Todd E Brandt wrote:
>> Adds trace events that give finer resolution into suspend/resume. These
>> events are graphed in the timelines generated by the analyze_suspend.py
>> script. They represent large areas of time consumed that are typical in
>> suspend and resume.
>>
>> The event is triggered by calling the function "trace_suspend_resume"
>> with two arguments: a string (the name of the event to be displayed
>> in the timeline), and a boolean (where true is used to denote the start
>> of the timeline event, and false to denote the end).
>>
>> Signed-off-by: Todd Brandt <todd.e.brandt@intel.com>
>> ---
>>  drivers/acpi/nvs.c           |  6 ++++++
>>  drivers/acpi/osl.c           |  3 +++
>>  drivers/base/syscore.c       |  5 +++++
>>  include/trace/events/power.h | 19 +++++++++++++++++++
>>  kernel/cpu.c                 |  9 +++++++++
>>  kernel/power/process.c       |  3 +++
>>  kernel/power/suspend.c       |  4 ++++
>>  7 files changed, 49 insertions(+)
>>
>> For more info see:
>> https://01.org/suspendresume/blogs/tebrandt/2014/custom-timeline-event-support-0
>>
>> I'm also interested to know if any tools depend on the machine_suspend
>> tracepoints, as this patch expands on the same info. I'd be willing to
>> merge the existing machine_suspend calls into this patch and rename
>> everything to suspend_resume provided it doesn't hurt any downstream tools.
>>
>> diff --git a/drivers/acpi/nvs.c b/drivers/acpi/nvs.c
>> index de4fe03..b52b686 100644
>> --- a/drivers/acpi/nvs.c
>> +++ b/drivers/acpi/nvs.c
>> @@ -12,6 +12,7 @@
>>  #include <linux/mm.h>
>>  #include <linux/slab.h>
>>  #include <linux/acpi.h>
>> +#include <trace/events/power.h>
>>  
>>  #include "internal.h"
>>  
>> @@ -171,6 +172,7 @@ int suspend_nvs_save(void)
>>  {
>>  	struct nvs_page *entry;
>>  
>> +	trace_suspend_resume("save_nvs_memory", true);
>>  	printk(KERN_INFO "PM: Saving platform NVS memory\n");
>>  
>>  	list_for_each_entry(entry, &nvs_list, node)
>> @@ -185,11 +187,13 @@ int suspend_nvs_save(void)
>>  			}
>>  			if (!entry->kaddr) {
>>  				suspend_nvs_free();
>> +				trace_suspend_resume("save_nvs_memory", false);
>>  				return -ENOMEM;
>>  			}
>>  			memcpy(entry->data, entry->kaddr, entry->size);
>>  		}
>>  
>> +	trace_suspend_resume("save_nvs_memory", false);
>>  	return 0;
>>  }
>>  
>> @@ -203,10 +207,12 @@ void suspend_nvs_restore(void)
>>  {
>>  	struct nvs_page *entry;
>>  
>> +	trace_suspend_resume("restore_nvs_memory", true);
>>  	printk(KERN_INFO "PM: Restoring platform NVS memory\n");
>>  
>>  	list_for_each_entry(entry, &nvs_list, node)
>>  		if (entry->data)
>>  			memcpy(entry->kaddr, entry->data, entry->size);
>> +	trace_suspend_resume("restore_nvs_memory", false);
>>  }
>>  #endif
>> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
>> index 6776c59..b65a77a 100644
>> --- a/drivers/acpi/osl.c
>> +++ b/drivers/acpi/osl.c
>> @@ -44,6 +44,7 @@
>>  #include <linux/list.h>
>>  #include <linux/jiffies.h>
>>  #include <linux/semaphore.h>
>> +#include <trace/events/power.h>
>>  
>>  #include <asm/io.h>
>>  #include <asm/uaccess.h>
>> @@ -835,7 +836,9 @@ acpi_status acpi_os_remove_interrupt_handler(u32 irq, acpi_osd_handler handler)
>>  
>>  void acpi_os_sleep(u64 ms)
>>  {
>> +	trace_suspend_resume("acpi_os_sleep", true);
>>  	msleep(ms);
>> +	trace_suspend_resume("acpi_os_sleep", false);
>>  }
> 
> This function doesn't have anything to do with system suspend/resume.
> It is for waiting. :-)
> 
> The rest of the patch looks OK to me.
> 
> Steven, what about the tracing angle?
> 

Hi Todd,

This might be a silly question, but the suspend_enter() function invokes
ftrace_stop() before suspending the machine, and restarts ftrace after
resume. And your patch seems to instrument code further down (deeper)
in the suspend/resume path (such as disable_nonboot_cpus() for example).
Doesn't the ftrace stop/start pose any problem for this patch?

Regards,
Srivatsa S. Bhat


>>  
>>  void acpi_os_stall(u32 us)
>> diff --git a/drivers/base/syscore.c b/drivers/base/syscore.c
>> index e8d11b6..c2fd5d4 100644
>> --- a/drivers/base/syscore.c
>> +++ b/drivers/base/syscore.c
>> @@ -10,6 +10,7 @@
>>  #include <linux/mutex.h>
>>  #include <linux/module.h>
>>  #include <linux/interrupt.h>
>> +#include <trace/events/power.h>
>>  
>>  static LIST_HEAD(syscore_ops_list);
>>  static DEFINE_MUTEX(syscore_ops_lock);
>> @@ -49,6 +50,7 @@ int syscore_suspend(void)
>>  	struct syscore_ops *ops;
>>  	int ret = 0;
>>  
>> +	trace_suspend_resume("syscore_suspend", true);
>>  	pr_debug("Checking wakeup interrupts\n");
>>  
>>  	/* Return error code if there are any wakeup interrupts pending. */
>> @@ -70,6 +72,7 @@ int syscore_suspend(void)
>>  				"Interrupts enabled after %pF\n", ops->suspend);
>>  		}
>>  
>> +	trace_suspend_resume("syscore_suspend", false);
>>  	return 0;
>>  
>>   err_out:
>> @@ -92,6 +95,7 @@ void syscore_resume(void)
>>  {
>>  	struct syscore_ops *ops;
>>  
>> +	trace_suspend_resume("syscore_resume", true);
>>  	WARN_ONCE(!irqs_disabled(),
>>  		"Interrupts enabled before system core resume.\n");
>>  
>> @@ -103,6 +107,7 @@ void syscore_resume(void)
>>  			WARN_ONCE(!irqs_disabled(),
>>  				"Interrupts enabled after %pF\n", ops->resume);
>>  		}
>> +	trace_suspend_resume("syscore_resume", false);
>>  }
>>  EXPORT_SYMBOL_GPL(syscore_resume);
>>  #endif /* CONFIG_PM_SLEEP */
>> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
>> index 9a7e08d..1d9fd76 100644
>> --- a/include/trace/events/power.h
>> +++ b/include/trace/events/power.h
>> @@ -151,6 +151,25 @@ TRACE_EVENT(device_pm_report_time,
>>  		__entry->ops_time, __entry->error)
>>  );
>>  
>> +TRACE_EVENT(suspend_resume,
>> +
>> +	TP_PROTO(char *action, bool start),
>> +
>> +	TP_ARGS(action, start),
>> +
>> +	TP_STRUCT__entry(
>> +		__string(action, action)
>> +		__field(bool, start)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__assign_str(action, action);
>> +		__entry->start = start;
>> +	),
>> +
>> +	TP_printk("%s %s", __get_str(action), (__entry->start)?"begin":"end")
>> +);
>> +
>>  DECLARE_EVENT_CLASS(wakeup_source,
>>  
>>  	TP_PROTO(const char *name, unsigned int state),
>> diff --git a/kernel/cpu.c b/kernel/cpu.c
>> index a9e710e..7aa30ec 100644
>> --- a/kernel/cpu.c
>> +++ b/kernel/cpu.c
>> @@ -20,6 +20,7 @@
>>  #include <linux/gfp.h>
>>  #include <linux/suspend.h>
>>  #include <linux/lockdep.h>
>> +#include <trace/events/power.h>
>>  
>>  #include "smpboot.h"
>>  
>> @@ -509,6 +510,7 @@ static cpumask_var_t frozen_cpus;
>>  int disable_nonboot_cpus(void)
>>  {
>>  	int cpu, first_cpu, error = 0;
>> +	char buf[12];
>>  
>>  	cpu_maps_update_begin();
>>  	first_cpu = cpumask_first(cpu_online_mask);
>> @@ -522,7 +524,10 @@ int disable_nonboot_cpus(void)
>>  	for_each_online_cpu(cpu) {
>>  		if (cpu == first_cpu)
>>  			continue;
>> +		sprintf(buf, "CPU%u_OFF", cpu);
>> +		trace_suspend_resume(buf, true);
>>  		error = _cpu_down(cpu, 1);
>> +		trace_suspend_resume(buf, false);
>>  		if (!error)
>>  			cpumask_set_cpu(cpu, frozen_cpus);
>>  		else {
>> @@ -554,6 +559,7 @@ void __weak arch_enable_nonboot_cpus_end(void)
>>  void __ref enable_nonboot_cpus(void)
>>  {
>>  	int cpu, error;
>> +	char buf[10];
>>  
>>  	/* Allow everyone to use the CPU hotplug again */
>>  	cpu_maps_update_begin();
>> @@ -566,7 +572,10 @@ void __ref enable_nonboot_cpus(void)
>>  	arch_enable_nonboot_cpus_begin();
>>  
>>  	for_each_cpu(cpu, frozen_cpus) {
>> +		sprintf(buf, "CPU%u_ON", cpu);
>> +		trace_suspend_resume(buf, true);
>>  		error = _cpu_up(cpu, 1);
>> +		trace_suspend_resume(buf, false);
>>  		if (!error) {
>>  			printk(KERN_INFO "CPU%d is up\n", cpu);
>>  			continue;
>> diff --git a/kernel/power/process.c b/kernel/power/process.c
>> index 06ec886..4aec2d9 100644
>> --- a/kernel/power/process.c
>> +++ b/kernel/power/process.c
>> @@ -17,6 +17,7 @@
>>  #include <linux/delay.h>
>>  #include <linux/workqueue.h>
>>  #include <linux/kmod.h>
>> +#include <trace/events/power.h>
>>  
>>  /* 
>>   * Timeout for stopping processes
>> @@ -175,6 +176,7 @@ void thaw_processes(void)
>>  	struct task_struct *g, *p;
>>  	struct task_struct *curr = current;
>>  
>> +	trace_suspend_resume("thaw_processes", true);
>>  	if (pm_freezing)
>>  		atomic_dec(&system_freezing_cnt);
>>  	pm_freezing = false;
>> @@ -201,6 +203,7 @@ void thaw_processes(void)
>>  
>>  	schedule();
>>  	printk("done.\n");
>> +	trace_suspend_resume("thaw_processes", false);
>>  }
>>  
>>  void thaw_kernel_threads(void)
>> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
>> index 8233cd4..c7e3e9f 100644
>> --- a/kernel/power/suspend.c
>> +++ b/kernel/power/suspend.c
>> @@ -147,7 +147,9 @@ static int suspend_prepare(suspend_state_t state)
>>  	if (error)
>>  		goto Finish;
>>  
>> +	trace_suspend_resume("freeze_processes", true);
>>  	error = suspend_freeze_processes();
>> +	trace_suspend_resume("freeze_processes", false);
>>  	if (!error)
>>  		return 0;
>>  
>> @@ -337,9 +339,11 @@ static int enter_state(suspend_state_t state)
>>  	if (state == PM_SUSPEND_FREEZE)
>>  		freeze_begin();
>>  
>> +	trace_suspend_resume("sync_filesystems", true);
>>  	printk(KERN_INFO "PM: Syncing filesystems ... ");
>>  	sys_sync();
>>  	printk("done.\n");
>> +	trace_suspend_resume("sync_filesystems", false);
>>  
>>  	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
>>  	error = suspend_prepare(state);