#10111: hp2ps silently discards samples -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Profiling | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider the following hp file: {{{ JOB "whatever" DATE "Sat Feb 21 12:56 2015" SAMPLE_UNIT "seconds" VALUE_UNIT "bytes" BEGIN_SAMPLE 0.00 MAIN 1000 END_SAMPLE 0.00 BEGIN_SAMPLE 0.00 MAIN 100 END_SAMPLE 0.00 BEGIN_SAMPLE 0.01 MAIN 500 END_SAMPLE 0.01 }}} hp2ps will generate a graph showing heap usage going from 100 bytes to 500 bytes... not 1000-100-500 as expected. This is because hp2ps only uses the last sample with the same timestamp. These hp files show in practice because GHC doesn't output BEGIN_SAMPLE entries with enough precision, see also https://phabricator.haskell.org/D679 to increase the precision. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10111 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler