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module/cpufreq: Fix async use_governor()

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use_governor() was trying to set concurrently both per-cpu and global tunables for
each governor, which lead to a write conflict.

Split the work into the per-governor global tunables and the per-cpu
tunables, and do all that in concurrently. Each task is therefore
responsible of a distinct set of files and all is well.

Also remove @memoized on async functions. It will be reintroduced in a
later commit when there is a safe alternative for async functions.
This commit is contained in:
Douglas Raillard 2022-07-26 14:42:33 +01:00 committed by Marc Bonnici
parent 2c4b16f280
commit 0ea9c73ec0
1 changed files with 78 additions and 38 deletions
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112
devlib/module/cpufreq.py
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@ -58,7 +58,6 @@ class CpufreqModule(Module):
super(CpufreqModule, self).__init__(target)
self._governor_tunables = {}
@memoized
@asyn.asyncf
async def list_governors(self, cpu):
"""Returns a list of governors supported by the cpu."""
@ -105,7 +104,7 @@ class CpufreqModule(Module):
raise TargetStableError('Governor {} not supported for cpu {}'.format(governor, cpu))
sysfile = '/sys/devices/system/cpu/{}/cpufreq/scaling_governor'.format(cpu)
await self.target.write_value.asyn(sysfile, governor)
return await self.set_governor_tunables.asyn(cpu, governor, **kwargs)
await self.set_governor_tunables.asyn(cpu, governor, **kwargs)
@asyn.asynccontextmanager
async def use_governor(self, governor, cpus=None, **kwargs):
@ -151,44 +150,83 @@ class CpufreqModule(Module):
try:
yield
finally:
async def set_gov(cpu):
async def set_per_cpu_tunables(cpu):
domain, prev_gov, tunables, freq = cpus_infos[cpu]
await self.set_governor.asyn(cpu, prev_gov, **tunables)
# Per-cpu tunables are safe to set concurrently
await self.set_governor_tunables.asyn(cpu, prev_gov, per_cpu=True, **tunables)
# Special case for userspace, frequency is not seen as a tunable
if prev_gov == "userspace":
await self.set_frequency.asyn(cpu, freq)
await self.target.async_manager.concurrently(
set_gov(cpu)
per_cpu_tunables = self.target.async_manager.concurrently(
set_per_cpu_tunables(cpu)
for cpu in domains
)
# Non-per-cpu tunables have to be set one after the other, for each
# governor that we had to deal with.
global_tunables = {
prev_gov: (cpu, tunables)
for cpu, (domain, prev_gov, tunables, freq) in cpus_infos.items()
}
global_tunables = self.target.async_manager.concurrently(
self.set_governor_tunables.asyn(cpu, gov, per_cpu=False, **tunables)
for gov, (cpu, tunables) in global_tunables.items()
)
# Set the governor first
await self.target.async_manager.concurrently(
self.set_governor.asyn(cpu, cpus_infos[cpu][1])
for cpu in domains
)
# And then set all the tunables concurrently. Each task has a
# specific and non-overlapping set of file to write.
await self.target.async_manager.concurrently(
(per_cpu_tunables, global_tunables)
)
@asyn.asyncf
async def _list_governor_tunables(self, cpu, governor=None):
if isinstance(cpu, int):
cpu = 'cpu{}'.format(cpu)
if governor is None:
governor = await self.get_governor.asyn(cpu)
try:
return self._governor_tunables[governor]
except KeyError:
for per_cpu, path in (
(True, '/sys/devices/system/cpu/{}/cpufreq/{}'.format(cpu, governor)),
# On old kernels
(False, '/sys/devices/system/cpu/cpufreq/{}'.format(governor)),
):
try:
tunables = await self.target.list_directory.asyn(path)
except TargetStableError:
continue
else:
break
else:
per_cpu = False
tunables = []
data = (governor, per_cpu, tunables)
self._governor_tunables[governor] = data
return data
@asyn.asyncf
async def list_governor_tunables(self, cpu):
"""Returns a list of tunables available for the governor on the specified CPU."""
if isinstance(cpu, int):
cpu = 'cpu{}'.format(cpu)
governor = await self.get_governor.asyn(cpu)
if governor not in self._governor_tunables:
try:
tunables_path = '/sys/devices/system/cpu/{}/cpufreq/{}'.format(cpu, governor)
self._governor_tunables[governor] = await self.target.list_directory.asyn(tunables_path)
except TargetStableError: # probably an older kernel
try:
tunables_path = '/sys/devices/system/cpu/cpufreq/{}'.format(governor)
self._governor_tunables[governor] = await self.target.list_directory.asyn(tunables_path)
except TargetStableError: # governor does not support tunables
self._governor_tunables[governor] = []
return self._governor_tunables[governor]
_, _, tunables = await self._list_governor_tunables.asyn(cpu)
return tunables
@asyn.asyncf
async def get_governor_tunables(self, cpu):
if isinstance(cpu, int):
cpu = 'cpu{}'.format(cpu)
governor, tunable_list = await self.target.async_manager.concurrently((
self.get_governor.asyn(cpu),
self.list_governor_tunables.asyn(cpu)
))
governor, _, tunable_list = await self._list_governor_tunables.asyn(cpu)
write_only = set(WRITE_ONLY_TUNABLES.get(governor, []))
tunable_list = [
@ -211,7 +249,7 @@ class CpufreqModule(Module):
return tunables
@asyn.asyncf
async def set_governor_tunables(self, cpu, governor=None, **kwargs):
async def set_governor_tunables(self, cpu, governor=None, per_cpu=None, **kwargs):
"""
Set tunables for the specified governor. Tunables should be specified as
keyword arguments. Which tunables and values are valid depends on the
@ -220,6 +258,9 @@ class CpufreqModule(Module):
:param cpu: The cpu for which the governor will be set. ``int`` or
full cpu name as it appears in sysfs, e.g. ``cpu0``.
:param governor: The name of the governor. Must be all lower case.
:param per_cpu: If ``None``, both per-cpu and global governor tunables
will be set. If ``True``, only per-CPU tunables will be set and if
``False``, only global tunables will be set.
The rest should be keyword parameters mapping tunable name onto the value to
be set for it.
@ -229,29 +270,28 @@ class CpufreqModule(Module):
tunable.
"""
if not kwargs:
return
if isinstance(cpu, int):
cpu = 'cpu{}'.format(cpu)
if governor is None:
governor = await self.get_governor.asyn(cpu)
valid_tunables = await self.list_governor_tunables.asyn(cpu)
governor, gov_per_cpu, valid_tunables = await self._list_governor_tunables.asyn(cpu, governor=governor)
for tunable, value in kwargs.items():
if tunable in valid_tunables:
if per_cpu is not None and gov_per_cpu != per_cpu:
pass
if gov_per_cpu:
path = '/sys/devices/system/cpu/{}/cpufreq/{}/{}'.format(cpu, governor, tunable)
try:
await self.target.write_value.asyn(path, value)
except TargetStableError:
if await self.target.file_exists.asyn(path):
# File exists but we did something wrong
raise
# Expected file doesn't exist, try older sysfs layout.
else:
path = '/sys/devices/system/cpu/cpufreq/{}/{}'.format(governor, tunable)
await self.target.write_value.asyn(path, value)
else:
message = 'Unexpected tunable {} for governor {} on {}.\n'.format(tunable, governor, cpu)
message += 'Available tunables are: {}'.format(valid_tunables)
raise TargetStableError(message)
@memoized
@asyn.asyncf
async def list_frequencies(self, cpu):
"""Returns a sorted list of frequencies supported by the cpu or an empty list