perf_counters: Initialize once only when needed #1656
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This works around some performance problems running Android under QEMU. Calling `pfm_initialize` was very slow, and was called during dynamic initialization (before `main` or when loaded as a shared library). This happened whenever benchmark was linked, even if no benchmarks were run. Instead, call `pfm_initialize` at most once, and only when one of: 1. `PerfCounters::Initialize` is called 2. `PerfCounters::Create` is called with a non-empty counter list 3. `PerfCounters::IsCounterSupported` is called The return value of the first `pfm_initialize()` is saved and returned from all subsequent `PerfCounters::Initialize` calls.
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jmr
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Aug 24, 2023
dmah42
approved these changes
Aug 24, 2023
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This works around some performance problems running Android under QEMU. Calling
pfm_initializewas very slow, and was called during dynamic initialization (beforemainor when loaded as a shared library). This happened whenever benchmark was linked, even if no benchmarks were run.Instead, call
pfm_initializeat most once, and only when one of:PerfCounters::Initializeis calledPerfCounters::Createis called with a non-empty counter listPerfCounters::IsCounterSupportedis calledThe return value of the first
pfm_initialize()is saved and returned from all subsequentPerfCounters::Initializecalls.