Timing function problem

[Lutz]

Yes, using your definition of 'merge', time is increasing on my system too.

Code Select Expand

> ./merge-time
2837.097
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
3596.99
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
4144.72
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
4526.995
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
5021.806
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
5475.793
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
5927.577
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
6196.546
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
6451.934
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
6576.566
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
8244.489
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
10133.406
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
7734.864
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
7595.829
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
9027.866
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
7656.296
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
7687.444
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
7974.064
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
8514.397000000001
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
8105.182
(598 576460752303423488 418 3 0 2048 0 10878 10705 1411)
~>

Also printing (sys-info) and you can see, there is no increase in stack levels or lisp cells between the calls to merge. I guess the answer is in stack and memory management of the underlying OS.

Code Select Expand

(dotimes (i 20)
(println (time (merge (sequence 1 500) (sequence 1 200) <) 500))
(println (sys-info)))

[cameyo]

Thanks Lutz.

Anyway i have found a strange thing: raising an error on REPL reset the time.

For example, type the following on REPL:

Code Select Expand

(set)
ERR: missing argument in function set
Now timing the function will restart the problem (but time is reset to first value 1750.432):

Code Select Expand

(time (merge (sequence 1 500) (sequence 1 200) <) 500)
;-> 1750.432
(time (merge (sequence 1 500) (sequence 1 200) <) 500)
;-> 2218.979
...

[Lutz]

Over time envrironment and stack memory gets fragmented by certain functions. The error forces a total low level freeing and reallocation of this memory. There is nothing we can do about it without slowing down everywhere, but it is a rare enough problem. Until now, I have never seen this before.

[rickyboy]

Over time envrironment and stack memory gets fragmented by certain functions. The error forces a total low level freeing and reallocation of this memory. There is nothing we can do about it without slowing down everywhere, but it is a rare enough problem. Until now, I have never seen this before.

Thanks, Lutz!

[cameyo]

Thanks, Lutz !

Grazie Lutz !