Re: array-copy! is slow & array-map.c (was: Extremly slow for format & string-join)

[Daniel Llorens]

On Apr 2, 2013, at 12:19, Daniel Llorens wrote:

> On Apr 1, 2013, at 19:15, Daniel Llorens wrote:
> 
>> Third, none of the above are causing the slowness of array-copy!. I noticed 
>> that there's a double indirection in racp(). The second patch removes it. 
>> Actually this double indirection goes on all over array-map.c and I don't 
>> understand why it's needed...
> 
> This patch does the same for array-fill!. The improvement is similar.

These two patches do it for array-map!.

The first patch avoids cons for the 1-argument case. The second patch removes 
the double indirection for the first two arguments in every case. Since there's 
some work done inside the loop, the improvement is smaller than for array-copy! 
or array-fill!.

Before the first patch:

scheme@(guile-user)> (define a (make-array 0. 1000000 10))
scheme@(guile-user)> (define b (make-array 0. 1000000 10))
scheme@(guile-user)> (define c (make-array *unspecified* 1000000 10))
scheme@(guile-user)> (define d (transpose-array (make-array *unspecified* 10 
1000000) 1 0))
scheme@(guile-user)> ,time (array-map! c (const 0.))
;; 0.558498s real time, 0.556974s run time.  0.000000s spent in GC.
scheme@(guile-user)> ,time (array-map! c values a)
;; 1.467717s real time, 1.463470s run time.  0.269786s spent in GC.
scheme@(guile-user)> ,time (array-map! c values d)
;; 1.500785s real time, 1.496482s run time.  0.254156s spent in GC.
scheme@(guile-user)> ,time (array-map! c (lambda (a b) (+ a b)) a b)
;; 2.278655s real time, 2.271948s run time.  0.528379s spent in GC.

After the first patch:

scheme@(guile-user)> (define a (make-array 0. 1000000 10))
scheme@(guile-user)> (define b (make-array 0. 1000000 10))
scheme@(guile-user)> (define c (make-array *unspecified* 1000000 10))
scheme@(guile-user)> (define d (transpose-array (make-array *unspecified* 10 
1000000) 1 0))
scheme@(guile-user)> ,time (array-map! c (const 0.))
;; 0.559337s real time, 0.557811s run time.  0.000000s spent in GC.
scheme@(guile-user)> ,time (array-map! c values a)
;; 1.038836s real time, 1.035859s run time.  0.134621s spent in GC.
scheme@(guile-user)> ,time (array-map! c values d)
;; 1.041937s real time, 1.039000s run time.  0.125787s spent in GC.
scheme@(guile-user)> ,time (array-map! c (lambda (a b) (+ a b)) a b)
;; 2.294594s real time, 2.287883s run time.  0.518576s spent in GC.

After both patches:

scheme@(guile-user)> (define a (make-array 0. 1000000 10))
scheme@(guile-user)> (define b (make-array 0. 1000000 10))
scheme@(guile-user)> (define c (make-array *unspecified* 1000000 10))
scheme@(guile-user)> (define d (transpose-array (make-array *unspecified* 10 
1000000) 1 0))
scheme@(guile-user)> ,time (array-map! c (const 0.))
;; 0.467621s real time, 0.466343s run time.  0.000000s spent in GC.
scheme@(guile-user)> ,time (array-map! c values a)
;; 0.823515s real time, 0.821152s run time.  0.135106s spent in GC.
scheme@(guile-user)> ,time (array-map! c values d)
;; 0.825138s real time, 0.822763s run time.  0.124970s spent in GC.
scheme@(guile-user)> ,time (array-map! c (lambda (a b) (+ a b)) a b)
;; 2.066735s real time, 2.060635s run time.  0.525089s spent in GC.

0005-Avoid-per-element-cons-for-1-arg-case-of-array-map.patch
Description: Binary data

0006-Remove-double-indirection-in-array-map-with-2-args.patch
Description: Binary data