Hi all,
recently I did some micro-benchmarks of parallel code on my 8-core
computer. But I don't get the point about this behaviour of pmap. Can
anyone explain this to me? The code is running on a dual quad-core
intel machine (Xeon X5482, 3.20 GHz).
(defn maptest [cores] (doall (map (fn [x] (dot
Sorry about the copy&paste error. I partially changed len to cores.
The code must look like:
(defn maptest [cores] (doall (map (fn [x] (dotimes [_ 10]
(inc
0))) (range cores
(defn pmaptest [cores] (doall (pmap (fn [x] (dotimes [_ 10]
(inc 0))) (range cores
and
(defn mapt
> My guess would be you're seeing the overhead for pmap since the
> (inc 0.1) computation is so cheap. From the docs for pmap:
> "Only useful for computationally intensive functions where the time of
> f dominates the coordination overhead."
I don't think so, as the cheap computation (inc 0.
> Could it be that your CPU has a single floating-point unit shared by 4
> cores on a single die, and thus only 2 floating-point units total for
> all 8 of your cores? If so, then that fact, plus the fact that each
> core has its own separate ALU for integer operations, would seem to
> explain th
> Johann, if you are still following this thread, could you try running
> this Clojure program on your 8 core machine?
>
> http://github.com/jafingerhut/clojure-benchmarks/blob/3e45bd8f6c3eba4...
>
> These first set of parameters below will do 8 jobs sequentially, each
> doing 10^10 (inc c)'s, whe
Hi everyone,
I need some help for loading in large data from file. For instance,
I'm trying to load from a text file one line of 5000 double values
(separated by comma). Having 8 byte per double I would assume this to
fit into ~400MB of memory, at least when using a java double array
internall
Hi and Thanks to all,
that helped a lot. I should definitely refactor my code using
transients. And the new vector-of is what I needed. The StringBuilder
trick saves lot of memory compared to a line split on very large
lines.
Thanks again,
Johann
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