These are Zircon's performance tests.
When using a standalone Zircon build the tests can be run with
/boot/test/sys/perf-test
When using a Fuchsia build you must first ensure the right package is included. Try building with
fx set core.x64 --with-base //bundles/buildbot:core && fx full-build
You can then run the tests with
/pkgfs/packages/garnet_benchmarks/0/test/sys/perf-test
For examples of how to use the testing framework, as well as coding guidelines, please read: perftest.h