mirror of
https://github.com/ceres-solver/ceres-solver.git
synced 2026-08-30 00:50:37 +08:00
Mike Vitus
f0c3b23684
Previously, the thread ID was acquired and released on every iteration of the for loop. The C++11 concurrent queue implementation is much slower than TBB's version and consequently this was a huge bottleneck. This introduces another ParallelFor API which takes the thread ID as a parameter in the evaluation function. This allows us to acquire and release the thread ID for each block of work which drastically improves the performance. This change brings us on par with OpenMP and TBB. See below for a timing comparison. Note: in this example this CLs C++11 version is faster to compute the residuals because TBB still must acquire the thread ID on every iteration, which has some overhead. Tested by building and running tests for no threading, OpenMP, TBB, and C++11 threads. Also ran bazel tests. ./bin/bundle_adjuster --input=problem-744-543562-pre.txt --num_threads=8 C++11 @Head Time (in seconds): Residual only evaluation 7.819692 (5) Jacobian & residual evaluation 11.606063 (6) Linear solver 47.860195 (5) Minimizer 70.877072 Total 90.806338 --------------------------------------------------- C++11 (This CL) Time (in seconds): Residual only evaluation 1.217500 (5) Jacobian & residual evaluation 5.796112 (6) Linear solver 44.080873 (5) Minimizer 54.635524 Total 77.640072 --------------------------------------------------- OpenMP Time (in seconds): Residual only evaluation 0.797023 (5) Jacobian & residual evaluation 5.633916 (6) Linear solver 43.280020 (5) Minimizer 53.199058 Total 76.250861 --------------------------------------------------- TBB Time (in seconds): Residual only evaluation 1.911095 (5) Jacobian & residual evaluation 5.557807 (6) Linear solver 44.074680 (5) Minimizer 55.002688 Total 78.052687 --------------------------------------------------- No Threads Time (in seconds): Residual only evaluation 2.939212 (5) Jacobian & residual evaluation 18.519874 (6) Linear solver 74.017837 (5) Minimizer 98.980080 Total 122.216391 Change-Id: I3af959b0771bbdfe8cad8c13896191d6ac903181
112 lines
4.2 KiB
C++
112 lines
4.2 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2017 Google Inc. All rights reserved.
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// http://ceres-solver.org/
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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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// * 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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// * 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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// * Neither the name of Google Inc. nor the names of its contributors may be
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// 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 OWNER 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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//
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// Author: yp@photonscore.de (Yury Prokazov)
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#ifndef CERES_INTERNAL_THREAD_TOKEN_PROVIDER_H_
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#define CERES_INTERNAL_THREAD_TOKEN_PROVIDER_H_
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#include "ceres/internal/config.h"
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#include "ceres/internal/port.h"
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#ifdef CERES_USE_TBB
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#include <tbb/concurrent_queue.h>
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#endif
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#ifdef CERES_USE_CXX11_THREADS
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#include "ceres/concurrent_queue.h"
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#endif
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namespace ceres {
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namespace internal {
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// Helper for TBB and C++11 thread number identification that is similar to
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// omp_get_thread_num() behaviour. This is necessary to support TBB and C++11
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// threading with a sequential thread id. This is used to access preallocated
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// resources in the parallelized code parts. The sequence of tokens varies from
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// 0 to num_threads - 1 that can be acquired to identify the thread in a thread
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// pool.
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//
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// If CERES_NO_THREADS is defined, Acquire() always returns 0 and Release()
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// takes no action.
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//
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// If CERES_USE_OPENMP, omp_get_thread_num() is used to Acquire() with no action
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// in Release()
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//
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//
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// Example usage pseudocode:
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//
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// ThreadTokenProvider ttp(N); // allocate N tokens
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// Spawn N threads {
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// int token = ttp.Acquire(); // get unique token
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// ...
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// ... use token to access resources bound to the thread
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// ...
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// ttp.Release(token); // return token to the pool
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// }
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//
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class ThreadTokenProvider {
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public:
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ThreadTokenProvider(int num_threads);
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// Returns the first token from the queue. The acquired value must be
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// given back by Release().
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//
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// With TBB this function will block if all the tokens are aquired by
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// concurent threads.
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int Acquire();
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// Makes previously acquired token available for other threads.
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void Release(int thread_id);
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private:
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#ifdef CERES_USE_TBB
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// This queue initially holds a sequence from 0..num_threads-1. Every
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// Acquire() call the first number is removed from here. When the token is not
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// needed anymore it shall be given back with corresponding Release() call.
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tbb::concurrent_bounded_queue<int> pool_;
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#endif
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#ifdef CERES_USE_CXX11_THREADS
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// This queue initially holds a sequence from 0..num_threads-1. Every
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// Acquire() call the first number is removed from here. When the token is not
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// needed anymore it shall be given back with corresponding Release()
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// call. This concurrent queue is more expensive than TBB's version, so you
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// should not acquire the thread ID on every for loop iteration.
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ConcurrentQueue<int> pool_;
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#endif
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ThreadTokenProvider(ThreadTokenProvider&);
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ThreadTokenProvider& operator=(ThreadTokenProvider&);
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};
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} // namespace internal
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} // namespace ceres
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#endif // CERES_INTERNAL_THREAD_TOKEN_PROVIDER_H_
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