cpuidle: Add 'above' and 'below' idle state metrics

Add two new metrics for CPU idle states, "above" and "below", to count
the number of times the given state had been asked for (or entered
from the kernel's perspective), but the observed idle duration turned
out to be too short or too long for it (respectively).

These metrics help to estimate the quality of the CPU idle governor
in use.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2018-12-10 12:30:23 +01:00
parent 9456823c84
commit 04dab58a39
5 changed files with 55 additions and 1 deletions

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@ -145,6 +145,8 @@ What: /sys/devices/system/cpu/cpuX/cpuidle/stateN/name
/sys/devices/system/cpu/cpuX/cpuidle/stateN/power
/sys/devices/system/cpu/cpuX/cpuidle/stateN/time
/sys/devices/system/cpu/cpuX/cpuidle/stateN/usage
/sys/devices/system/cpu/cpuX/cpuidle/stateN/above
/sys/devices/system/cpu/cpuX/cpuidle/stateN/below
Date: September 2007
KernelVersion: v2.6.24
Contact: Linux power management list <linux-pm@vger.kernel.org>
@ -166,6 +168,11 @@ Description:
usage: (RO) Number of times this state was entered (a count).
above: (RO) Number of times this state was entered, but the
observed CPU idle duration was too short for it (a count).
below: (RO) Number of times this state was entered, but the
observed CPU idle duration was too long for it (a count).
What: /sys/devices/system/cpu/cpuX/cpuidle/stateN/desc
Date: February 2008

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@ -398,6 +398,16 @@ deeper the (effective) idle state represented by it. Each of them contains
a number of files (attributes) representing the properties of the idle state
object corresponding to it, as follows:
``above``
Total number of times this idle state had been asked for, but the
observed idle duration was certainly too short to match its target
residency.
``below``
Total number of times this idle state had been asked for, but cerainly
a deeper idle state would have been a better match for the observed idle
duration.
``desc``
Description of the idle state.

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@ -202,7 +202,6 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
struct cpuidle_state *target_state = &drv->states[index];
bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
ktime_t time_start, time_end;
s64 diff;
/*
* Tell the time framework to switch to a broadcast timer because our
@ -248,6 +247,9 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
local_irq_enable();
if (entered_state >= 0) {
s64 diff, delay = drv->states[entered_state].exit_latency;
int i;
/*
* Update cpuidle counters
* This can be moved to within driver enter routine,
@ -260,6 +262,33 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
dev->last_residency = (int)diff;
dev->states_usage[entered_state].time += dev->last_residency;
dev->states_usage[entered_state].usage++;
if (diff < drv->states[entered_state].target_residency) {
for (i = entered_state - 1; i >= 0; i--) {
if (drv->states[i].disabled ||
dev->states_usage[i].disable)
continue;
/* Shallower states are enabled, so update. */
dev->states_usage[entered_state].above++;
break;
}
} else if (diff > delay) {
for (i = entered_state + 1; i < drv->state_count; i++) {
if (drv->states[i].disabled ||
dev->states_usage[i].disable)
continue;
/*
* Update if a deeper state would have been a
* better match for the observed idle duration.
*/
if (diff - delay >= drv->states[i].target_residency)
dev->states_usage[entered_state].below++;
break;
}
}
} else {
dev->last_residency = 0;
}

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@ -301,6 +301,8 @@ define_show_state_str_function(name)
define_show_state_str_function(desc)
define_show_state_ull_function(disable)
define_store_state_ull_function(disable)
define_show_state_ull_function(above)
define_show_state_ull_function(below)
define_one_state_ro(name, show_state_name);
define_one_state_ro(desc, show_state_desc);
@ -310,6 +312,8 @@ define_one_state_ro(power, show_state_power_usage);
define_one_state_ro(usage, show_state_usage);
define_one_state_ro(time, show_state_time);
define_one_state_rw(disable, show_state_disable, store_state_disable);
define_one_state_ro(above, show_state_above);
define_one_state_ro(below, show_state_below);
static struct attribute *cpuidle_state_default_attrs[] = {
&attr_name.attr,
@ -320,6 +324,8 @@ static struct attribute *cpuidle_state_default_attrs[] = {
&attr_usage.attr,
&attr_time.attr,
&attr_disable.attr,
&attr_above.attr,
&attr_below.attr,
NULL
};

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@ -33,6 +33,8 @@ struct cpuidle_state_usage {
unsigned long long disable;
unsigned long long usage;
unsigned long long time; /* in US */
unsigned long long above; /* Number of times it's been too deep */
unsigned long long below; /* Number of times it's been too shallow */
#ifdef CONFIG_SUSPEND
unsigned long long s2idle_usage;
unsigned long long s2idle_time; /* in US */