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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Part of the PsychoPy library
# Copyright (C) 2002-2018 Jonathan Peirce (C) 2019-2020 Open Science Tools Ltd.
# Distributed under the terms of the GNU General Public License (GPL).
"""Placeholder for adding c (or ctypes) extensions to PsychoPy on linux.
"""
from __future__ import absolute_import, print_function
from psychopy import logging
import sys
try:
import ctypes
import ctypes.util
c = ctypes.cdll.LoadLibrary(ctypes.util.find_library('c'))
importCtypesFailed = False
except Exception:
importCtypesFailed = True
logging.debug("rush() not available because import ctypes, ctypes.util "
"failed in psychopy/platform_specific/linux.py")
# FIFO and RR(round-robin) allow highest priority for realtime
SCHED_NORMAL = 0
SCHED_FIFO = 1
SCHED_RR = 2
SCHED_BATCH = 3
if not importCtypesFailed:
class _SchedParams(ctypes.Structure):
_fields_ = [('sched_priority', ctypes.c_int)]
warnMax = """Could not raise thread priority with sched_setscheduler.
To enable rush(), if you are using a debian-based Linux, try this:
'sudo setcap cap_sys_nice=eip %s' [NB: install 'setcap' first.]
If you are using the system's python (eg /usr/bin/python2.x), its highly
recommended to change cap_sys_nice back to normal afterwards:
'sudo setcap cap_sys_nice= %s'"""
warnNormal = ("Failed to set thread priority to normal with "
"sched_setscheduler.\n"
"Try: 'sudo setcap cap_sys_nice= %s'")
def rush(value=True, realtime=False):
"""Raise the priority of the current thread/process using
- sched_setscheduler
realtime arg is not used in Linux implementation.
NB for rush() to work on (debian-based?) Linux requires that the
script is run using a copy of python that is allowed to change
priority, eg: sudo setcap cap_sys_nice=eip <sys.executable>,
and maybe restart PsychoPy. If <sys.executable> is the system python,
it's important to restore it back to normal to avoid possible
side-effects. Alternatively, use a different python executable,
and change its cap_sys_nice.
For RedHat-based systems, 'sudo chrt ...' at run-time might be
needed instead, not sure.
see http://rt.et.redhat.com/wiki/images/8/8e/Rtprio.pdf
"""
if importCtypesFailed:
return False
if value: # set to RR with max priority
schedParams = _SchedParams()
schedParams.sched_priority = c.sched_get_priority_max(SCHED_RR)
err = c.sched_setscheduler(0, SCHED_RR, ctypes.byref(schedParams))
if err == -1: # returns 0 if OK
logging.warning(warnMax % (sys.executable, sys.executable))
else: # set to RR with normal priority
schedParams = _SchedParams()
schedParams.sched_priority = c.sched_get_priority_min(SCHED_NORMAL)
err = c.sched_setscheduler(0, SCHED_NORMAL, ctypes.byref(schedParams))
if err == -1: # returns 0 if OK
logging.warning(warnNormal % sys.executable)
return True
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