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[Thread Backend]Fix CPU Thread Binding for Multiple Sockets #5918

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merged 2 commits into from Jun 25, 2020
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[Thread Backend]Fix CPU Thread Binding for Multiple Sockets #5918

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2f75f2a
Fix CPU Thread Binding for Multiple Sockets
kevinthesun Jun 24, 2020
c03d46d
Backward compatibility
kevinthesun Jun 24, 2020
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10 changes: 2 additions & 8 deletions src/runtime/threading_backend.cc
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Expand Up @@ -159,14 +159,8 @@ class ThreadGroup::Impl {
CPU_SET(sorted_order_[sorted_order_.size() - i - 1], &cpuset);
}
} else {
int big_count = big_count_;
// Imagine our x86 has cores 0 - 7
// physical cores are 0 - 3, logical cores are 4 - 7, big_count_ is 8
// we wish we run on physical cores, not logical cores to avoid contention issue.
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The big count might be necessary for the big.little ARM targets

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Is this possible to detect big.LITTLE somewhere?

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@tqchen tqchen Jun 24, 2020 •
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We need to look into the code. Perhaps do num_binds = std::min(MaxConcurrency(), big_count_); to keep backward compact for BIG.LITTLE

#if defined(_M_X64) || defined(__x86_64__)
big_count /= 2; // ignore hyper-threading
#endif
for (int i = 0; i < big_count; ++i) {
int num_cpu_workers = std::min(MaxConcurrency(), big_count_);
for (int i = 0; i < num_cpu_workers; ++i) {
CPU_SET(sorted_order_[i], &cpuset);
}
}
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