GitLab

Add 2 benchmarks:

1. Performance of thread creation/exiting in presence of breakpoints.
2. Performance of breakpoint modification in presence of threads.

The benchmarks capture use cases that we are interested in:
using inheritable breakpoints in large highly-threaded applications.

The benchmarks show significant slowdown imposed by breakpoints
(even when they don't fire).

Testing on Intel 8173M with 112 HW threads show:

  perf bench --repeat=56 breakpoint thread --breakpoints=0 --parallelism=56 --threads=20
        78.675000 usecs/op
  perf bench --repeat=56 breakpoint thread --breakpoints=4 --parallelism=56 --threads=20
     12967.135714 usecs/op

That's 165x slowdown due to presence of the breakpoints.

  perf bench --repeat=20000 breakpoint enable --passive=0 --active=0
         1.433250 usecs/op
  perf bench --repeat=20000 breakpoint enable --passive=224 --active=0
       585.318400 usecs/op
  perf bench --repeat=20000 breakpoint enable --passive=0 --active=...