/usr/lib/python3/dist-packages/pyopencl/characterize/__init__.py is in python3-pyopencl 2017.2.2-1.
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__copyright__ = "Copyright (C) 2009 Andreas Kloeckner"
__license__ = """
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
import pyopencl as cl
from pytools import memoize
import six
from six.moves import range, zip
class CLCharacterizationWarning(UserWarning):
pass
@memoize
def has_double_support(dev):
for ext in dev.extensions.split(" "):
if ext == "cl_khr_fp64":
return True
return False
def has_amd_double_support(dev):
""""Fix to allow incomplete amd double support in low end boards"""
for ext in dev.extensions.split(" "):
if ext == "cl_amd_fp64":
return True
return False
def reasonable_work_group_size_multiple(dev, ctx=None):
try:
return dev.warp_size_nv
except Exception:
pass
if ctx is None:
ctx = cl.Context([dev])
prg = cl.Program(ctx, """
__kernel void knl(__global float *a)
{
a[get_global_id(0)] = 0;
}
""")
prg.build()
return prg.knl.get_work_group_info(
cl.kernel_work_group_info.PREFERRED_WORK_GROUP_SIZE_MULTIPLE,
dev)
def nv_compute_capability(dev):
"""If *dev* is an Nvidia GPU :class:`pyopencl.Device`, return a tuple
*(major, minor)* indicating the device's compute capability.
"""
try:
return (dev.compute_capability_major_nv,
dev.compute_capability_minor_nv)
except Exception:
return None
def usable_local_mem_size(dev, nargs=None):
"""Return an estimate of the usable local memory size.
:arg nargs: Number of 32-bit arguments passed.
"""
usable_local_mem_size = dev.local_mem_size
nv_compute_cap = nv_compute_capability(dev)
if (nv_compute_cap is not None
and nv_compute_cap < (2, 0)):
# pre-Fermi use local mem for parameter passing
if nargs is None:
# assume maximum
usable_local_mem_size -= 256
else:
usable_local_mem_size -= 4*nargs
return usable_local_mem_size
def simultaneous_work_items_on_local_access(dev):
"""Return the number of work items that access local
memory simultaneously and thereby may conflict with
each other.
"""
nv_compute_cap = nv_compute_capability(dev)
if nv_compute_cap is not None:
if nv_compute_cap < (2, 0):
return 16
else:
if nv_compute_cap >= (3, 0):
from warnings import warn
warn("wildly guessing conflicting local access size on '%s'"
% dev,
CLCharacterizationWarning)
return 32
if dev.type & cl.device_type.GPU:
from warnings import warn
warn("wildly guessing conflicting local access size on '%s'"
% dev,
CLCharacterizationWarning)
return 16
elif dev.type & cl.device_type.CPU:
return 1
else:
from warnings import warn
warn("wildly guessing conflicting local access size on '%s'"
% dev,
CLCharacterizationWarning)
return 16
def local_memory_access_granularity(dev):
"""Return the number of bytes per bank in local memory."""
return 4
def local_memory_bank_count(dev):
"""Return the number of banks present in local memory.
"""
nv_compute_cap = nv_compute_capability(dev)
if nv_compute_cap is not None:
if nv_compute_cap < (2, 0):
return 16
else:
if nv_compute_cap >= (3, 0):
from warnings import warn
warn("wildly guessing local memory bank count on '%s'"
% dev,
CLCharacterizationWarning)
return 32
if dev.type & cl.device_type.GPU:
from warnings import warn
warn("wildly guessing local memory bank count on '%s'"
% dev,
CLCharacterizationWarning)
return 16
elif dev.type & cl.device_type.CPU:
if dev.local_mem_type == cl.device_local_mem_type.GLOBAL:
raise RuntimeError("asking for a bank count is "
"meaningless for cache-based lmem")
from warnings import warn
warn("wildly guessing conflicting local access size on '%s'"
% dev,
CLCharacterizationWarning)
return 16
def why_not_local_access_conflict_free(dev, itemsize,
array_shape, array_stored_shape=None):
"""
:param itemsize: size of accessed data in bytes
:param array_shape: array dimensions, fastest-moving last
(C order)
:returns: a tuple (multiplicity, explanation), where *multiplicity*
is the number of work items that will conflict on a bank when accessing
local memory. *explanation* is a string detailing the found conflict.
"""
# FIXME: Treat 64-bit access on NV CC 2.x + correctly
if array_stored_shape is None:
array_stored_shape = array_shape
rank = len(array_shape)
array_shape = array_shape[::-1]
array_stored_shape = array_stored_shape[::-1]
gran = local_memory_access_granularity(dev)
if itemsize != gran:
from warnings import warn
warn("local conflict info might be inaccurate "
"for itemsize != %d" % gran,
CLCharacterizationWarning)
sim_wi = simultaneous_work_items_on_local_access(dev)
bank_count = local_memory_bank_count(dev)
conflicts = []
for work_item_axis in range(rank):
bank_accesses = {}
for work_item_id in range(sim_wi):
addr = 0
addr_mult = itemsize
idx = []
left_over_idx = work_item_id
for axis, (ax_size, ax_stor_size) in enumerate(
zip(array_shape, array_stored_shape)):
if axis >= work_item_axis:
left_over_idx, ax_idx = divmod(left_over_idx, ax_size)
addr += addr_mult*ax_idx
idx.append(ax_idx)
else:
idx.append(0)
addr_mult *= ax_stor_size
if left_over_idx:
# out-of-bounds, assume not taking place
continue
bank = (addr // gran) % bank_count
bank_accesses.setdefault(bank, []).append(
"w.item %s -> %s" % (work_item_id, idx[::-1]))
conflict_multiplicity = max(
len(acc) for acc in six.itervalues(bank_accesses))
if conflict_multiplicity > 1:
for bank, acc in six.iteritems(bank_accesses):
if len(acc) == conflict_multiplicity:
conflicts.append(
(conflict_multiplicity,
"%dx conflict on axis %d (from right, 0-based): "
"%s access bank %d" % (
conflict_multiplicity,
work_item_axis,
", ".join(acc), bank)))
if conflicts:
return max(conflicts)
else:
return 1, None
def get_fast_inaccurate_build_options(dev):
"""Return a list of flags valid on device *dev* that enable fast, but
potentially inaccurate floating point math.
"""
result = ["-cl-mad-enable", "-cl-fast-relaxed-math",
"-cl-no-signed-zeros", ]
if dev.vendor.startswith("Advanced Micro") or dev.vendor.startswith("NVIDIA"):
result.append("-cl-strict-aliasing")
return result
def get_simd_group_size(dev, type_size):
"""Return an estimate of how many work items will be executed across SIMD
lanes. This returns the size of what Nvidia calls a warp and what AMD calls
a wavefront.
Only refers to implicit SIMD.
:arg type_size: number of bytes in vector entry type.
"""
try:
return dev.warp_size_nv
except Exception:
pass
lc_vendor = dev.platform.vendor.lower()
if "nvidia" in lc_vendor:
return 32
if ("advanced micro" in lc_vendor or "ati" in lc_vendor):
if dev.type & cl.device_type.GPU:
# Tomasz Rybak says, in response to reduction mishbehaving on the AMD
# 'Loveland' APU:
#
# Like in CUDA reduction bug (related to Fermi) it again seems
# to be related to too eager concurrency when reducing results.
# According to http://oscarbg.blogspot.com/2009/10/news-from-web.html
# "Actually the wavefront size is only 64 for the highend cards(48XX,
# 58XX, 57XX), but 32 for the middleend cards and 16 for the lowend
# cards."
# IMO we should use PREFERRED_WORK_GROUP_SIZE_MULTIPLE to get
# non_sync_size. At the same size we lose SIMD CPU optimisation,
# but I do not know for now how to fix those two at the same time.
# Attached patch fixes problem on Loveland, not breaking anything on
# NVIDIA ION.
# This is therefore our best guess as to the SIMD group size.
return reasonable_work_group_size_multiple(dev)
elif dev.type & cl.device_type.CPU:
return 1
else:
raise RuntimeError("unexpected AMD device type")
if dev.type & cl.device_type.CPU:
# implicit assumption: Impl. will vectorize
return 1
return None
def get_pocl_version(platform, fallback_value=None):
if platform.name != "Portable Computing Language":
return None
import re
ver_match = re.match(
r"^OpenCL [0-9.]+ pocl ([0-9]+)\.([0-9]+)", platform.version)
if ver_match is None:
msg = ("pocl version number did not have expected format: '%s'"
% platform.version)
if fallback_value is not None:
from warnings import warn
warn(msg)
return fallback_value
else:
raise ValueError(msg)
else:
return (int(ver_match.group(1)), int(ver_match.group(2)))
_CHECK_FOR_POCL_ARG_COUNT_BUG_CACHE = {}
def _check_for_pocl_arg_count_bug(dev, ctx=None):
try:
return _CHECK_FOR_POCL_ARG_COUNT_BUG_CACHE[dev]
except KeyError:
pass
if ctx is None:
build_ctx = cl.Context([dev])
else:
build_ctx = ctx
prg = cl.Program(build_ctx, """
struct two_things
{
long a;
long b;
};
__kernel void test_knl(struct two_things x)
{
}
""").build()
result = prg.test_knl.num_args == 2
_CHECK_FOR_POCL_ARG_COUNT_BUG_CACHE[dev] = result
return result
def has_struct_arg_count_bug(dev, ctx=None):
"""Checks whether the device is expected to have the
`argument counting bug <https://github.com/pocl/pocl/issues/197>`_.
"""
if dev.platform.name == "Apple" and dev.type & cl.device_type.CPU:
return "apple"
if dev.platform.name == "Portable Computing Language":
pocl_version = get_pocl_version(dev.platform, fallback_value=(0.14))
if pocl_version <= (0, 13):
return "pocl"
elif pocl_version <= (0, 14) and _check_for_pocl_arg_count_bug(dev, ctx):
return "pocl"
return False
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