HSBencher.MeasureProcess

This module provides tools to time a sub-process (benchmark), including a facility for self-reporting execution time and reporting garbage collector overhead.

Documentation

measureProcess :: LineHarvester -> LineHarvester -> CommandDescr -> IO SubProcess

This runs a sub-process and tries to determine how long it took (real time) and how much of that time was spent in the mutator vs. the garbage collector.

It is complicated by:

1. An additional protocol for the process to report self-measured realtime (a line starting in SELFTIMED)
2. Parsing the output of +RTS -s to retrieve productivity OR using lines of the form PRODUCTIVITY: XYZ

Note that +RTS -s is specific to Haskell/GHC, but the PRODUCTIVITY tag allows non-haskell processes to report garbage collector overhead.

This procedure is currently not threadsafe, because it changes the current working directory.

selftimedHarvester :: LineHarvester

Check for a SELFTIMED line of output.

ghcProductivityHarvester :: LineHarvester

Retrieve productivity (i.e. percent time NOT garbage collecting) as output from a Haskell program with +RTS -s. Productivity is a percentage (double between 0.0 and 100.0, inclusive).

taggedLineHarvester :: ByteString -> LineHarvester

Check for a line of output of the form TAG NUM or TAG: NUM.

nullHarvester :: LineHarvester