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utils.py
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###################################################################
# Numexpr - Fast numerical array expression evaluator for NumPy.
#
# License: MIT
# Author: See AUTHORS.txt
#
# See LICENSE.txt and LICENSES/*.txt for details about copyright and
# rights to use.
####################################################################
import logging
log = logging.getLogger(__name__)
import os
import subprocess
import platform
from numexpr.interpreter import _set_num_threads, _get_num_threads, MAX_THREADS
from numexpr import use_vml
from . import version
if use_vml:
from numexpr.interpreter import (
_get_vml_version, _set_vml_accuracy_mode, _set_vml_num_threads,
_get_vml_num_threads)
def get_vml_version():
"""
Get the VML/MKL library version.
"""
if use_vml:
return _get_vml_version()
else:
return None
def set_vml_accuracy_mode(mode):
"""
Set the accuracy mode for VML operations.
The `mode` parameter can take the values:
- 'high': high accuracy mode (HA), <1 least significant bit
- 'low': low accuracy mode (LA), typically 1-2 least significant bits
- 'fast': enhanced performance mode (EP)
- None: mode settings are ignored
This call is equivalent to the `vmlSetMode()` in the VML library.
See:
http://www.intel.com/software/products/mkl/docs/webhelp/vml/vml_DataTypesAccuracyModes.html
for more info on the accuracy modes.
Returns old accuracy settings.
"""
if use_vml:
acc_dict = {None: 0, 'low': 1, 'high': 2, 'fast': 3}
acc_reverse_dict = {1: 'low', 2: 'high', 3: 'fast'}
if mode not in list(acc_dict.keys()):
raise ValueError(
"mode argument must be one of: None, 'high', 'low', 'fast'")
retval = _set_vml_accuracy_mode(acc_dict.get(mode, 0))
return acc_reverse_dict.get(retval)
else:
return None
def set_vml_num_threads(nthreads):
"""
Suggests a maximum number of threads to be used in VML operations.
This function is equivalent to the call
`mkl_domain_set_num_threads(nthreads, MKL_DOMAIN_VML)` in the MKL
library. See:
http://www.intel.com/software/products/mkl/docs/webhelp/support/functn_mkl_domain_set_num_threads.html
for more info about it.
"""
if use_vml:
_set_vml_num_threads(nthreads)
pass
def get_vml_num_threads():
"""
Gets the maximum number of threads to be used in VML operations.
This function is equivalent to the call
`mkl_domain_get_max_threads (MKL_DOMAIN_VML)` in the MKL
library. See:
http://software.intel.com/en-us/node/522118
for more info about it.
"""
if use_vml:
return _get_vml_num_threads()
return None
def set_num_threads(nthreads):
"""
Sets a number of threads to be used in operations.
DEPRECATED: returns the previous setting for the number of threads.
During initialization time NumExpr sets this number to the number
of detected cores in the system (see `detect_number_of_cores()`).
"""
old_nthreads = _set_num_threads(nthreads)
return old_nthreads
def get_num_threads():
"""
Gets the number of threads currently in use for operations.
"""
return _get_num_threads()
def _init_num_threads():
"""
Detects the environment variable 'NUMEXPR_MAX_THREADS' to set the threadpool
size, and if necessary the slightly redundant 'NUMEXPR_NUM_THREADS' or
'OMP_NUM_THREADS' env vars to set the initial number of threads used by
the virtual machine.
"""
# Any platform-specific short-circuits
if 'sparc' in version.platform_machine:
log.warning('The number of threads have been set to 1 because problems related '
'to threading have been reported on some sparc machine. '
'The number of threads can be changed using the "set_num_threads" '
'function.')
set_num_threads(1)
return 1
env_configured = False
n_cores = detect_number_of_cores()
if 'NUMEXPR_MAX_THREADS' in os.environ:
# The user has configured NumExpr in the expected way, so suppress logs.
env_configured = True
n_cores = MAX_THREADS
else:
# The use has not set 'NUMEXPR_MAX_THREADS', so likely they have not
# configured NumExpr as desired, so we emit info logs.
if n_cores > MAX_THREADS:
log.info('Note: detected %d virtual cores but NumExpr set to maximum of %d, check "NUMEXPR_MAX_THREADS" environment variable.'%(n_cores, MAX_THREADS))
if n_cores > 8:
# The historical 'safety' limit.
log.info('Note: NumExpr detected %d cores but "NUMEXPR_MAX_THREADS" not set, so enforcing safe limit of 8.'%n_cores)
n_cores = 8
# Now we check for 'NUMEXPR_NUM_THREADS' or 'OMP_NUM_THREADS' to set the
# actual number of threads used.
if 'NUMEXPR_NUM_THREADS' in os.environ:
requested_threads = int(os.environ['NUMEXPR_NUM_THREADS'])
elif 'OMP_NUM_THREADS' in os.environ:
requested_threads = int(os.environ['OMP_NUM_THREADS'])
else:
requested_threads = n_cores
if not env_configured:
log.info('NumExpr defaulting to %d threads.'%n_cores)
# The C-extension function performs its own checks against `MAX_THREADS`
set_num_threads(requested_threads)
return requested_threads
def detect_number_of_cores():
"""
Detects the number of cores on a system. Cribbed from pp.
"""
# Linux, Unix and MacOS:
if hasattr(os, "sysconf"):
if "SC_NPROCESSORS_ONLN" in os.sysconf_names:
# Linux & Unix:
ncpus = os.sysconf("SC_NPROCESSORS_ONLN")
if isinstance(ncpus, int) and ncpus > 0:
return ncpus
else: # OSX:
return int(subprocess.check_output(["sysctl", "-n", "hw.ncpu"]))
# Windows:
try:
ncpus = int(os.environ.get("NUMBER_OF_PROCESSORS", ""))
if ncpus > 0:
return ncpus
except ValueError:
pass
return 1 # Default
def detect_number_of_threads():
"""
DEPRECATED: use `_init_num_threads` instead.
If this is modified, please update the note in: https://github.com/pydata/numexpr/wiki/Numexpr-Users-Guide
"""
log.warning('Deprecated, use `init_num_threads` instead.')
try:
nthreads = int(os.environ.get('NUMEXPR_NUM_THREADS', ''))
except ValueError:
try:
nthreads = int(os.environ.get('OMP_NUM_THREADS', ''))
except ValueError:
nthreads = detect_number_of_cores()
# Check that we don't surpass the MAX_THREADS in interpreter.cpp
if nthreads > MAX_THREADS:
nthreads = MAX_THREADS
return nthreads
class CacheDict(dict):
"""
A dictionary that prevents itself from growing too much.
"""
def __init__(self, maxentries):
self.maxentries = maxentries
super(CacheDict, self).__init__(self)
def __setitem__(self, key, value):
# Protection against growing the cache too much
if len(self) > self.maxentries:
# Remove a 10% of (arbitrary) elements from the cache
entries_to_remove = self.maxentries // 10
for k in list(self.keys())[:entries_to_remove]:
super(CacheDict, self).__delitem__(k)
super(CacheDict, self).__setitem__(key, value)