Google benchmark state.PauseTiming() and state.ResumeTiming() take a long time - benchmarking

Question

I am running some performance tests using google benchmark API. I use state.PauseTiming() and state.ResumeTiming() to avoid unnecessary code segments runs through perf path. I have attached the sample code below
while (state.KeepRunning()) {
state.PauseTiming();
state.ResumeTiming();
state.PauseTiming();
state.ResumeTiming();
}
Those functions itself took 323ns for 2 pauses and resumes.
hiRun on (16 X 3196.36 MHz CPU s)
2019-06-19 11:21:06
---------------------------------------------------------------
Benchmark Time CPU Iterations
---------------------------------------------------------------
Benchmark_Test1 323 ns 324 ns 2158319
It this a bug in google benchmark API or are there any workarounds for this?

Answer 1

I had a similar use case and I noticed that the pause and resume has a lot of overhead, this is mentioned in their docs as well.
The workaround for this is another feature of Google Benchmarks. Manually measure the part of the code you want running time for inside the for loop. You can do this using manual timers (https://github.com/google/benchmark#cpu-timers).
You take chrono timestamps before and after the code segment for which you want running times and then you you set it to the state on each iterating using SetIterationTime.
When you call this test you need to add a ->UseManualTime();