75 lines
2.1 KiB
Python
75 lines
2.1 KiB
Python
"""Utilities for reading real time clocks and keeping soft real time constraints."""
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import os
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import time
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import platform
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import subprocess
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import multiprocessing
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from cffi import FFI
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from common.common_pyx import sec_since_boot # pylint: disable=no-name-in-module, import-error
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# time step for each process
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DT_CTRL = 0.01 # controlsd
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DT_MDL = 0.05 # model
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DT_DMON = 0.1 # driver monitoring
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DT_TRML = 0.5 # thermald and manager
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ffi = FFI()
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ffi.cdef("long syscall(long number, ...);")
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libc = ffi.dlopen(None)
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def set_realtime_priority(level):
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if os.getuid() != 0:
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print("not setting priority, not root")
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return
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if platform.machine() == "x86_64":
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NR_gettid = 186
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elif platform.machine() == "aarch64":
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NR_gettid = 178
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else:
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raise NotImplementedError
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tid = libc.syscall(NR_gettid)
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return subprocess.call(['chrt', '-f', '-p', str(level), str(tid)])
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class Ratekeeper():
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def __init__(self, rate, print_delay_threshold=0.):
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"""Rate in Hz for ratekeeping. print_delay_threshold must be nonnegative."""
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self._interval = 1. / rate
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self._next_frame_time = sec_since_boot() + self._interval
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self._print_delay_threshold = print_delay_threshold
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self._frame = 0
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self._remaining = 0
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self._process_name = multiprocessing.current_process().name
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@property
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def frame(self):
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return self._frame
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@property
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def remaining(self):
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return self._remaining
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# Maintain loop rate by calling this at the end of each loop
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def keep_time(self):
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lagged = self.monitor_time()
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if self._remaining > 0:
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time.sleep(self._remaining)
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return lagged
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# this only monitor the cumulative lag, but does not enforce a rate
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def monitor_time(self):
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lagged = False
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remaining = self._next_frame_time - sec_since_boot()
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self._next_frame_time += self._interval
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if self._print_delay_threshold is not None and remaining < -self._print_delay_threshold:
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print("%s lagging by %.2f ms" % (self._process_name, -remaining * 1000))
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lagged = True
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self._frame += 1
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self._remaining = remaining
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return lagged
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