perf: multiple mmap of fd behavior on x86/ARM

Vince Weaver
2017-08-10T18:49:06Z

So I was working on my perf_event_tests on ARM/ARM64 (the end goal was to
get ARM64 rdpmc support working, but apparently those patches never made
it upstream?)

anyway one test was failing due to an x86/arm difference, which is
possibly only tangentially perf related.

On x86 you can mmap() a perf_event_open() file descriptor multiple times
and it works.

On ARM/ARM64 you can only mmap() it once, any other attempts fail.

Is this expected behavior?

You can run the
tests/record_sample/mmap_multiple
test in the current git of my perf_event_tests testsuite for a testcase.

Vince