#7091: DPH Matrix product memory usage --------------------------------------------+--------------------------- Reporter: mblanco | Owner: benl Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: Data Parallel Haskell | Version: 7.4.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86 Type of failure: Runtime performance bug | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------------+--------------------------- Comment (by George): More specifially, in section 5.5 the paper states: nested parallelism can increase the asymptotic space complexity in a way that this paper does not address [15, 19]. ... The flattened version is a hylomorphism that first computes O(n{{{^}}}2) distances before reducing them to determine the maximum. Whereas the sequential version would run in O(n) space, the flattened version needs O(n{{{^}}}2) space to hold the intermediate vector of distances. Given the preceding this issue seems to be a known consequence of the dph algorithm and as such the status of this should be "Not a bug" as it is not a GHC bug. However this is just my opinion and I don't feel I have the expertise to actually change the bug status -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7091#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler