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cpustate: ensure known initial state

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cpustate result processor generates a view of the cpu subsystem power
state during execution of a workload from cpu_idle and cpu_frequency
ftraces. There exists a period before the first events in those
categories are seen where the state of the cpu subsystem is (partially)
unknown and it is reported as such by the result processor.

Unknown state usually exists for a relatively short period of time and
is generally not a big deal. For certain kinds of workloads, however, it
may constitude a significant protion of the trace.

Changes in this commit attempt to deal with this by a) reading starting
cpu frequencies and writing them into the trace, and b) nudging each
core to bring it out of idle; this happens before the start marker, so
that the system state between the markers should be completely known.
This commit is contained in:
Sergei Trofimov
2016-02-04 15:33:46 +00:00
parent 5e3cc8fcb5
commit 3a99a284c4
2 changed files with 73 additions and 8 deletions
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32
wlauto/result_processors/cpustate.py
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@@ -18,9 +18,11 @@ import csv
from collections import OrderedDict
from wlauto import ResultProcessor, Parameter
from wlauto.core import signal
from wlauto.exceptions import ConfigError
from wlauto.instrumentation import instrument_is_installed
from wlauto.utils.power import report_power_stats
from wlauto.utils.misc import unique
class CpuStatesProcessor(ResultProcessor):
@@ -115,8 +117,10 @@ class CpuStatesProcessor(ResultProcessor):
def initialize(self, context):
# pylint: disable=attribute-defined-outside-init
device = context.device
if not device.has('cpuidle'):
raise ConfigError('Device does not appear to have cpuidle capability; is the right module installed?')
for modname in ['cpuidle', 'cpufreq']:
if not device.has(modname):
message = 'Device does not appear to have {} capability; is the right module installed?'
raise ConfigError(message.format(modname))
if not device.core_names:
message = '{} requires"core_names" and "core_clusters" to be specified for the device.'
raise ConfigError(message.format(self.name))
@@ -126,6 +130,30 @@ class CpuStatesProcessor(ResultProcessor):
self.idle_state_names = [idle_states[i] for i in sorted(idle_states.keys())]
self.num_idle_states = len(self.idle_state_names)
self.iteration_reports = OrderedDict()
# priority -19: just higher than the slow_start of instrumentation
signal.connect(self.set_initial_state, signal.BEFORE_WORKLOAD_EXECUTION, priority=-19)
def set_initial_state(self, context):
# TODO: this does not play well with hotplug but leaving as-is, as this will be changed with
# the devilib port anyway.
# Write initial frequencies into the trace.
# NOTE: this assumes per-cluster DVFS, that is valid for devices that
# currently exist. This will need to be updated for per-CPU DFS.
self.logger.debug('Writing initial frequencies into trace...')
device = context.device
cluster_freqs = {}
for c in unique(device.core_clusters):
cluster_freqs[c] = device.get_cluster_cur_frequency(c)
for i, c in enumerate(device.core_clusters):
entry = 'CPU {} FREQUENCY: {} kHZ'.format(i, cluster_freqs[c])
device.set_sysfile_value('/sys/kernel/debug/tracing/trace_marker',
entry, verify=False)
# Nudge each cpu to force idle state transitions in the trace
self.logger.debug('Nudging all cores awake...')
for i in xrange(len(device.core_names)):
command = device.busybox + ' taskset 0x{:x} {}'
device.execute(command.format(1 << i, 'ls'))
def process_iteration_result(self, result, context):
trace = context.get_artifact('txttrace')