terry mcintyre wrote:
Has anyone looked at the resultant distributions, to
determine how "random" they are?
They should be run against the dieharder tests before any confidence is
placed in them. But I did look at them "visually" to see if there was
anything wrong that was immediately obvious to me. Visual inspection may
find an obvious bug, but it's not worth much after that.
If I could get van Kessel's numbers I would consider packaging it up and
running it through the diharder tests, but otherwise I see no reason
since I am not yet happy with the performance.
- Don
--- Don Dailey <[EMAIL PROTECTED]> wrote:
#include <stdio.h>
#include <stdlib.h>
I'm including my code below. Also, here are my
reported times:
Without RDTSC
real 0m1.008s
user 0m0.668s
sys 0m0.004s
With RDTSC
real 0m5.790s
user 0m3.956s
sys 0m0.016s
To turn on or off RDTSC see the rdtsc_rand line
that says, "if (1)"
- Don
----------[ snip ]------------
#define rdtscll(val) \
__asm__ __volatile__("rdtsc" : "=A" (val))
unsigned long long rdtsc_rand(void);
/******************************************************/
unsigned long long rdtsc_rand(void)
{
static unsigned long long
val=0x0000000011111111ULL;
unsigned long long new = 0llu;
if (1) {
rdtscll(new);
}
val ^= (val >> 15) ^ (val << 14) ^ 9 ^ new;
return val;
}
void kessel()
{
int i;
unsigned long long last = 0;
unsigned long long cur = 0;
for (i=100000000; i>0; i--) {
cur = rdtsc_rand();
if (i <= 10) {
printf("%20llu %20lld\n", cur, (int) cur -
last);
}
last = cur;
}
}
int main(int argc, char **argv)
{
kessel();
return(0);
}
A van Kessel wrote:
I would like to mention that your generator is 64
bit and the other
That is correct.
My timings (Haven't profiled yet):
WITH TSC:
real 0m0.902s
user 0m0.870s
sys 0m0.002s
WITHOUT:
real 0m0.613s
user 0m0.582s
sys 0m0.000s
That's for 100 M random numbers.
And inlining would probably help a lot, too.
AvK
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Terry McIntyre <[EMAIL PROTECTED]>
“Wherever is found what is called a paternal government, there is found state
education. It has been discovered that the best way to insure implicit
obedience is to commence tyranny in the nursery.”
Benjamin Disraeli, Speech in the House of Commons [June 15, 1874]
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