Eliminate harness measurement distortion in TransferCache benchmarks. - #1022
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BM_InsertRange, BM_RemoveRange, BM_RealisticBatchNonBatchMutations, and BM_RealisticHitRate in transfer_cache_benchmark invoked state.PauseTiming() and state.ResumeTiming() inside every iteration of the benchmark loop, spending ~60% of CPU cycles in clock_gettime/vDSO syscall overhead (~1300 ns/iter) and obscuring the underlying 10-30 ns cache operations. In addition, FakeTransferCacheEnvironment::Insert and Remove allocated temporary std::vector instances on the heap in each call. Amortize setup across batches with state.KeepRunningBatch in BM_InsertRange and BM_RemoveRange, precompute PRNG decisions in BM_RealisticBatchNonBatchMutations and BM_RealisticHitRate using compile-time constant modulo, and replace dynamic std::vector buffers with stack arrays in FakeTransferCacheEnvironment. PiperOrigin-RevId: 985469423
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Eliminate harness measurement distortion in TransferCache benchmarks.
BM_InsertRange, BM_RemoveRange, BM_RealisticBatchNonBatchMutations, and
BM_RealisticHitRate in transfer_cache_benchmark invoked state.PauseTiming()
and state.ResumeTiming() inside every iteration of the benchmark loop,
spending ~60% of CPU cycles in clock_gettime/vDSO syscall overhead (~1300 ns/iter)
and obscuring the underlying 10-30 ns cache operations. In addition,
FakeTransferCacheEnvironment::Insert and Remove allocated temporary std::vector
instances on the heap in each call.
Amortize setup across batches with state.KeepRunningBatch in BM_InsertRange and
BM_RemoveRange, precompute PRNG decisions in BM_RealisticBatchNonBatchMutations
and BM_RealisticHitRate using compile-time constant modulo, and replace dynamic
std::vector buffers with stack arrays in FakeTransferCacheEnvironment.