Interesting results... For vaddx, garbage collection time just about
doubles when you add 3 random vectors, but vadd actually
*decreases*? That seems odd to me.
On May 18, 2009, at 4:10 AM, gabor papp wrote:
As long as it doesn't impact performance, please feel free to
improve
i am testing the performance of vector operators and comparing them to
simple macros that can handle every vector sizes. i attached a vadd
test. it turns out that it is even a bit faster than the c++ version,
probably due to the scheme->c conversion overhead.
adding 2 random vectors:
vadd: 0.00564 0.00783 0.0007
vaddx: 0.00401 0.00724 0.00056
adding 3 random vectors:
vadd: 0.00608 0.01074 0.00064
vaddx: 0.00489 0.00951 0.00108
the results are calculated by adding the vectors 100000 times and
calculating the average time needed to execute the instructions.
vadd is
the current vector addition fluxus uses, vaddx is the macro attached.
the three numbers are: the number of milliseconds of CPU time required
to obtain this result, the number of "real" milliseconds required for
the result, and the number of milliseconds of CPU time spent on
garbage
collection.
what do you think? can we change the vector operations to more
flexible
scheme versions or am i overlooking something?
best,
gabor
----------------------------
(define (vadd2 a b)
(build-vector (vector-length a)
(lambda (i)
(+ (vector-ref a i)
(vector-ref b i)))))
(define-syntax vaddx
(syntax-rules ()
[(vaddx a b) (vadd2 a b)]
[(vaddx a b c ...) (vadd2 a (vaddx b c ...))]))
(define (profile f n)
(let ([timing-info
(map (lambda (x)
(exact->inexact (/ x n)))
(foldl (lambda (vl al)
(map + vl al))
(list 0 0 0)
(for/list ([i (in-range n)])
(let-values ([(v cpu user gc) (time-apply f
'())])
(list cpu user gc)))))])
(printf "~a ~a ~a~n" (list-ref timing-info 0)
(list-ref timing-info 1)
(list-ref timing-info 2))))
(display "vadd: ")
(profile (lambda () (vadd (rndvec) (rndvec))) 100000)
(display "vaddx: ")
(profile (lambda () (vaddx (rndvec) (rndvec))) 100000)
Evan Raskob
Top Floor
4-8 Arcola Street
London E8 2DJ
United Kingdom
