On Thu, 2013-03-28 at 01:05 -0400, Mark H Weaver wrote: > Nala Ginrut <nalagin...@gmail.com> writes: > > > But I'm still puzzled with the performance of par-map: > > --------------------cut------------------- > > scheme@(guile-user)> ,time (define a (map (lambda (x) (expt x 5)) (iota > > 10000))) > > ;; 0.008019s real time, 0.007979s run time. 0.000000s spent in GC. > > scheme@(guile-user)> ,time (define a (par-map (lambda (x) (expt x 5)) > > (iota 10000))) > > ;; 6.596471s real time, 6.579375s run time. 1.513880s spent in GC. > > --------------------end------------------- > > > > So my question is, what's the proper scenario to use par-map? > > It only makes sense to use 'par-map' when the procedure is fairly > expensive to compute. There is inevitably a lot of overhead in creating > and joining the threads. Granted, we should be able to do much better > than we're doing now, but it would *never* make sense to use 'par-map' > when each computation is as simple as (expt x 5). >
Well, is there any example? And there're two possible applications: 1. handle the requests in a server 2. read files from disk (but how big file is proper for par-map) Are these ways heavy enough for par-map? Potentially, I inclined to use the lovely delimited-continuation to handle the requests, but seems ludo think this way is slower? Or there's improvement room? > Regards, > Mark
