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Fix for massively parallel performance regression (#720)
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* Fix for massively parallel performance regression
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@JDBetteridge
JDBetteridge authored May 8, 2024
1 parent ebbed56 commit 7bef38f
Showing 1 changed file with 85 additions and 89 deletions.
174 changes: 85 additions & 89 deletions pyop2/compilation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,7 @@ def _check_hashes(x, y, datatype):


def set_default_compiler(compiler):
"""Set the PyOP2 default compiler, globally.
"""Set the PyOP2 default compiler, globally over COMM_WORLD.
:arg compiler: String with name or path to compiler executable
OR a subclass of the Compiler class
Expand All @@ -85,66 +85,73 @@ def set_default_compiler(compiler):
)


def sniff_compiler(exe):
def sniff_compiler(exe, comm=mpi.COMM_WORLD):
"""Obtain the correct compiler class by calling the compiler executable.
:arg exe: String with name or path to compiler executable
:arg comm: Comm over which we want to determine the compiler type
:returns: A compiler class
"""
try:
output = subprocess.run(
[exe, "--version"],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
check=True,
encoding="utf-8"
).stdout
except (subprocess.CalledProcessError, UnicodeDecodeError):
output = ""

# Find the name of the compiler family
if output.startswith("gcc") or output.startswith("g++"):
name = "GNU"
elif output.startswith("clang"):
name = "clang"
elif output.startswith("Apple LLVM") or output.startswith("Apple clang"):
name = "clang"
elif output.startswith("icc"):
name = "Intel"
elif "Cray" in output.split("\n")[0]:
# Cray is more awkward eg:
# Cray clang version 11.0.4 (<some_hash>)
# gcc (GCC) 9.3.0 20200312 (Cray Inc.)
name = "Cray"
else:
name = "unknown"

# Set the compiler instance based on the platform (and architecture)
if sys.platform.find("linux") == 0:
if name == "Intel":
compiler = LinuxIntelCompiler
elif name == "GNU":
compiler = LinuxGnuCompiler
elif name == "clang":
compiler = LinuxClangCompiler
elif name == "Cray":
compiler = LinuxCrayCompiler
compiler = None
if comm.rank == 0:
# Note:
# Sniffing compiler for very large numbers of MPI ranks is
# expensive so we do this on one rank and broadcast
try:
output = subprocess.run(
[exe, "--version"],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
check=True,
encoding="utf-8"
).stdout
except (subprocess.CalledProcessError, UnicodeDecodeError):
output = ""

# Find the name of the compiler family
if output.startswith("gcc") or output.startswith("g++"):
name = "GNU"
elif output.startswith("clang"):
name = "clang"
elif output.startswith("Apple LLVM") or output.startswith("Apple clang"):
name = "clang"
elif output.startswith("icc"):
name = "Intel"
elif "Cray" in output.split("\n")[0]:
# Cray is more awkward eg:
# Cray clang version 11.0.4 (<some_hash>)
# gcc (GCC) 9.3.0 20200312 (Cray Inc.)
name = "Cray"
else:
compiler = AnonymousCompiler
elif sys.platform.find("darwin") == 0:
if name == "clang":
machine = platform.uname().machine
if machine == "arm64":
compiler = MacClangARMCompiler
elif machine == "x86_64":
compiler = MacClangCompiler
elif name == "GNU":
compiler = MacGNUCompiler
name = "unknown"

# Set the compiler instance based on the platform (and architecture)
if sys.platform.find("linux") == 0:
if name == "Intel":
compiler = LinuxIntelCompiler
elif name == "GNU":
compiler = LinuxGnuCompiler
elif name == "clang":
compiler = LinuxClangCompiler
elif name == "Cray":
compiler = LinuxCrayCompiler
else:
compiler = AnonymousCompiler
elif sys.platform.find("darwin") == 0:
if name == "clang":
machine = platform.uname().machine
if machine == "arm64":
compiler = MacClangARMCompiler
elif machine == "x86_64":
compiler = MacClangCompiler
elif name == "GNU":
compiler = MacGNUCompiler
else:
compiler = AnonymousCompiler
else:
compiler = AnonymousCompiler
else:
compiler = AnonymousCompiler
return compiler

return comm.bcast(compiler, 0)


class Compiler(ABC):
Expand Down Expand Up @@ -178,8 +185,8 @@ class Compiler(ABC):
_debugflags = ()

def __init__(self, extra_compiler_flags=(), extra_linker_flags=(), cpp=False, comm=None):
# Get compiler version ASAP since it is used in __repr__
self.sniff_compiler_version()
# Set compiler version ASAP since it is used in __repr__
self.version = None

self._extra_compiler_flags = tuple(extra_compiler_flags)
self._extra_linker_flags = tuple(extra_linker_flags)
Expand All @@ -190,6 +197,7 @@ def __init__(self, extra_compiler_flags=(), extra_linker_flags=(), cpp=False, co
# Compilation communicators are reference counted on the PyOP2 comm
self.pcomm = mpi.internal_comm(comm, self)
self.comm = mpi.compilation_comm(self.pcomm, self)
self.sniff_compiler_version()

def __repr__(self):
return f"<{self._name} compiler, version {self.version or 'unknown'}>"
Expand Down Expand Up @@ -238,23 +246,28 @@ def sniff_compiler_version(self, cpp=False):
:arg cpp: If set to True will use the C++ compiler rather than
the C compiler to determine the version number.
"""
# Note:
# Sniffing the compiler version for very large numbers of
# MPI ranks is expensive
exe = self.cxx if cpp else self.cc
self.version = None
# `-dumpversion` is not sufficient to get the whole version string (for some compilers),
# but other compilers do not implement `-dumpfullversion`!
for dumpstring in ["-dumpfullversion", "-dumpversion"]:
try:
output = subprocess.run(
[exe, dumpstring],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
check=True,
encoding="utf-8"
).stdout
self.version = Version(output)
break
except (subprocess.CalledProcessError, UnicodeDecodeError, InvalidVersion):
continue
version = None
if self.comm.rank == 0:
# `-dumpversion` is not sufficient to get the whole version string (for some compilers),
# but other compilers do not implement `-dumpfullversion`!
for dumpstring in ["-dumpfullversion", "-dumpversion"]:
try:
output = subprocess.run(
[exe, dumpstring],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
check=True,
encoding="utf-8"
).stdout
version = Version(output)
break
except (subprocess.CalledProcessError, UnicodeDecodeError, InvalidVersion):
continue
self.version = self.comm.bcast(version, 0)

@property
def bugfix_cflags(self):
Expand Down Expand Up @@ -448,23 +461,6 @@ class LinuxGnuCompiler(Compiler):
_optflags = ("-march=native", "-O3", "-ffast-math")
_debugflags = ("-O0", "-g")

def sniff_compiler_version(self, cpp=False):
super(LinuxGnuCompiler, self).sniff_compiler_version()
if self.version >= Version("7.0"):
try:
# gcc-7 series only spits out patch level on dumpfullversion.
exe = self.cxx if cpp else self.cc
output = subprocess.run(
[exe, "-dumpfullversion"],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
check=True,
encoding="utf-8"
).stdout
self.version = Version(output)
except (subprocess.CalledProcessError, UnicodeDecodeError, InvalidVersion):
pass

@property
def bugfix_cflags(self):
"""Flags to work around bugs in compilers."""
Expand Down Expand Up @@ -596,7 +592,7 @@ def __init__(self, code, argtypes):
exe = configuration["cxx"] or "mpicxx"
else:
exe = configuration["cc"] or "mpicc"
compiler = sniff_compiler(exe)
compiler = sniff_compiler(exe, comm)
dll = compiler(cppargs, ldargs, cpp=cpp, comm=comm).get_so(code, extension)

if isinstance(jitmodule, GlobalKernel):
Expand Down

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