I forgot to mention, I cut the number of reverse iterations down to 1000 (not 10000) so I wouldn't have to wait too long for criterium, the speedup numbers are representative of the full test though.
Cameron. On Sunday, December 9, 2012 6:26:16 PM UTC+11, cameron wrote: > > > Interesting problem, the slowdown seems to being caused by the reverse > call (actually the calls to conj with a list argument). > Calling conj in a multi-threaded environment seems to have a significant > performance impact when using lists > I created some alternate reverse implementations (the fastest uses a > vector and cons), the gist with the test code can be found at > https://gist.github.com/4243724 > > On a dual Xeon E5520 (8 physical cores) @ 2.27GHz with Linux runnning > OpenJDK 1.7.0_09 I got the following results: > > fast-reverse : map-ms: 3.3, pmap-ms 0.7, speedup 4.97 > list-cons : map-ms: 4.0, pmap-ms 0.7, speedup 6.13 > vec-conj : map-ms: 4.0, pmap-ms 1.3, speedup 3.10 > list-conj : map-ms: 10.8, pmap-ms 21.2, speedup 0.51 > clojure-reverse : map-ms: 13.5, pmap-ms 26.8, speedup 0.50 (this is > equivalent to the original code) > > The following JDK command line options were used: > "-Xmx20G" "-XX:MaxPermSize=8G" "-XX:+UseParallelGC" > "-XX:+UseParallelOldGC" > > Some other notes: > I ran the sample under YourKit and garbage collection represents a small > percentage of execution time in both single and multi-threaded tests, there > are no blocked threads for the duration of the test and there is no > unexpected monitor/lock usage. > > Cheers, > Cameron. > > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
