(PECL xhprof >= 0.9.0) Start xhprof profiler
(PECL xhprof >= 0.9.0) Start XHProf profiling in sampling mode
(PECL xhprof >= 0.9.0) Stops xhprof profiler
(PECL xhprof >= 0.9.0) Stops xhprof sample profiler