perf_event_open failed with: Operation not supported on webbench

[racardoso]

When use webbench to run a simple fibonnaci test on HHVM it warning lots of perf_event_open failed with: Operation not supported on webbench. Also the test have variable performance. Sometime we don't get those errors and the test runs with a reasonable performance. But when we got lot's of this warnings (usually the number of warnings it's equal the number of clients passed as -c parameter to webbench) we have bad results (sometimes 0 success and 0 fails). But HHVM doesn't crash and there's nothing else on hhvm.log.

This problem seems to affect X86_64 too.

HHVM Version

Any version 3.18 or higher or master, next branch

Standalone code, or other way to reproduce the problem

Download webbench: git clone https://github.com/EZLippi/WebBench

cd WebBench
sudo make
sudo make install

Run HHVM in server mode

hhvm -m server -p <port> &

can be 8000, 8080 Run the following code test_cpu.php on webbench ``` ``` ``` webbench -c 20 -t 60 http://localhost: ``` ### Expected result No operation not supported. No 0 success 0 fails ### Actual result perf_event_open failed with: Operation not supported perf_event_open failed with: Operation not supported perf_event_open failed with: Operation not supported perf_event_open failed with: Operation not supported perf_event_open failed with: Operation not supported perf_event_open failed with: Operation not supported ...

[leitao]

Any update on this topic?