oeqa.buildperf: method for measuring system resource usage
Extend BuildPerfTest class with a new method for measuring the system
resource usage of a shell command to BuildPerfTest class. For now,
easurement of the elapsed time is done with the Gnu time utility,
similarly to the build-perf-test.sh shell script. And, it currently only
records the elapsed (wall clock).
The measured values (currently, only the elapsed time) is actually a
dictionary, making it possible to extend it with additional resource
values, e.g. cpu time or i/o usage, in the future. In addition to the
actual values of the measurement each record contains a 'name' and
'legend' where name is supposed to function as a common key or id over
test runs, making comparison and trending easier, for example. Legend is
supposed to be a short human readable description.
Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
