ansible: new multiplexer/workers configuration
Following on from 152effc26c9a5918cb7ead7a97fe7fa7f81b6764,
* Pin mux to CPU 0
* Pin top-level CPU 1
* Pin workers sequentially to CPU 2..n
Nets 19.5% improvement on issue_140__thread_pileup.yml when targetting
64 Docker containers on the same 8 core/16 thread machine.
Before (prior to last scheme, no affinity at all):
2294528.731458 task-clock (msec) # 6.443 CPUs utilized
10,429,745 context-switches # 0.005 M/sec
2,049,618 cpu-migrations # 0.893 K/sec
8,258,952 page-faults # 0.004 M/sec
5,532,719,253,824 cycles # 2.411 GHz (83.35%)
3,267,471,616,230 instructions # 0.59 insn per cycle
# 1.22 stalled cycles per insn (83.35%)
662,006,455,943 branches # 288.515 M/sec (83.33%)
39,453,895,977 branch-misses # 5.96% of all branches (83.37%)
356.148064576 seconds time elapsed
After:
2226463.958975 task-clock (msec) # 7.784 CPUs utilized
9,831,466 context-switches # 0.004 M/sec
180,065 cpu-migrations # 0.081 K/sec
5,082,278 page-faults # 0.002 M/sec
5,592,548,587,259 cycles # 2.512 GHz (83.35%)
3,135,038,855,414 instructions # 0.56 insn per cycle
# 1.32 stalled cycles per insn (83.32%)
636,397,509,232 branches # 285.833 M/sec (83.30%)
39,135,441,790 branch-misses # 6.15% of all branches (83.35%)
286.036681644 seconds time elapsed
pull/564/head
David Wilson
6 years ago
parent
8f6e6b3940
commit
c6d5aa29ba
@ -0,0 +1,132 @@
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# Copyright 2017, David Wilson
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its contributors
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# may be used to endorse or promote products derived from this software without
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# specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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import ctypes
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import mmap
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import multiprocessing
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import os
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import struct
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import mitogen.parent
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try:
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_libc = ctypes.CDLL(None, use_errno=True)
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_strerror = _libc.strerror
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_strerror.restype = ctypes.c_char_p
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_pthread_mutex_init = _libc.pthread_mutex_init
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_pthread_mutex_lock = _libc.pthread_mutex_lock
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_pthread_mutex_unlock = _libc.pthread_mutex_unlock
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_sched_setaffinity = _libc.sched_setaffinity
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except (OSError, AttributeError):
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_libc = None
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class pthread_mutex_t(ctypes.Structure):
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_fields_ = [
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('data', ctypes.c_uint8 * 512),
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]
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def init(self):
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if _pthread_mutex_init(self.data, 0):
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raise Exception(_strerror(ctypes.get_errno()))
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def acquire(self):
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if _pthread_mutex_lock(self.data):
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raise Exception(_strerror(ctypes.get_errno()))
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def release(self):
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if _pthread_mutex_unlock(self.data):
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raise Exception(_strerror(ctypes.get_errno()))
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class State(ctypes.Structure):
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_fields_ = [
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('lock', pthread_mutex_t),
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('counter', ctypes.c_uint8),
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]
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class Manager(object):
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"""
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Bind this process to a randomly selected CPU. If done prior to starting
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threads, all threads will be bound to the same CPU. This call is a no-op on
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systems other than Linux.
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A hook is installed that causes `reset_affinity(clear=True)` to run in the
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child of any process created with :func:`mitogen.parent.detach_popen`,
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ensuring CPU-intensive children like SSH are not forced to share the same
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core as the (otherwise potentially very busy) parent.
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Threads bound to the same CPU share cache and experience the lowest
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possible inter-thread roundtrip latency, for example ensuring the minimum
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possible time required for :class:`mitogen.service.Pool` to interact with
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:class:`mitogen.core.Broker`, as required for every message transmitted or
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received.
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Binding threads of a Python process to one CPU makes sense, as they are
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otherwise unable to operate in parallel, and all must acquire the same lock
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prior to executing.
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"""
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def __init__(self):
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self.mem = mmap.mmap(-1, 4096)
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self.state = State.from_buffer(self.mem)
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self.state.lock.init()
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def _set_affinity(self, mask):
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mitogen.parent._preexec_hook = self.clear
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s = struct.pack('L', mask)
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_sched_setaffinity(os.getpid(), len(s), s)
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def cpu_count(self):
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return multiprocessing.cpu_count()
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def clear(self):
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"""
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Clear any prior binding, except for reserved CPUs.
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"""
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self._set_affinity(0xffffffff & ~3)
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def set_cpu(self, cpu):
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"""
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Bind to 0-based `cpu`.
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"""
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self._set_affinity(1 << cpu)
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def assign(self):
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self.state.lock.acquire()
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try:
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n = self.state.counter
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self.state.counter += 1
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finally:
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self.state.lock.release()
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self.set_cpu(2 + (n % (self.cpu_count() - 2)))
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manager = Manager()
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Loading…
Reference in New Issue