Re: Stack based allocation vs. Dynamic allocation

[aaro@iki.fi (Aaro Koskinen)]

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gisle@struts.ii.uib.no (Gisle S�lensminde) writes:
> gisle@gekko:116> time heap
> Time: 0:53.92 real   31.250 user   12.190 sys   80.5%
> 
> gisle@gekko:120> time stack
> Time: 0:11.02 real   10.490 user   0.030 sys   95.4%
> 
> The stack program was 3 times faster if you consider user times.
> In my tests the system time used was always at least 11 seconds,
> while the stack program never used more than 0.05 seconds. The 
> system have to work harder when using heap allocation, which makes
> the heap program run in only 1/4th of the time of the stack program.

The huge amount of used system time is interesting, since the
allocated data is always of the same size - there shouldn't be any
need for another system call after the first "new". Unless the "free"
releases the memory back to the operating system. (Most of C library
implementations I've seen do not usually shrunk the process' heap on
free()).

-- 
Aaro Koskinen, aaro@iki.fi, http://www.iki.fi/aaro