On Thu, 20 Mar 2003, Bernd Petrovitsch wrote:
> Tim Schmielau <tim@physik3.uni-rostock.de> wrote:
> >On Thu, 20 Mar 2003, Richard B. Johnson wrote:
> >
> >> unsigned long amount = 0L;
> >
> >try 'volatile' to get the deviation down...
>
> .. and try "long long" to avoid an overrun.
>
> Bernd
> --
Yes. That's better. It may have been a diagnostic error
in the code of the first person reporting this --also.
The data-rate is so high that I might have wrapped several
times! I didn't think it would be that high, only 2 to 3
gigibyte/second, not over 4 Gb/s (with 130MHz RAM no less)
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#define BUF_LEN 0x10000
volatile unsigned long long amount = 0L;
void timer(int unused) {
fprintf(stdout, "Kilobytes / sec = %llu\n", amount >> 10);
fflush(stdout);
amount = 0LL;
alarm(1);
}
int main() {
int fd, len;
char *buf;
if((fd = open("/dev/null", O_RDWR)) < 0)
exit(EXIT_FAILURE);
if((buf = malloc(BUF_LEN)) == NULL)
exit(EXIT_FAILURE);
(void)signal(SIGALRM, timer);
alarm(1);
while((len = write(fd, buf, BUF_LEN)) > 0)
amount += (unsigned long long) len;
free(buf);
return 0;
}
With network:
Kilobytes / sec = 46170080
Kilobytes / sec = 46171576
Kilobytes / sec = 46172944
Kilobytes / sec = 46172192
Kilobytes / sec = 46171840
Kilobytes / sec = 46171576
Without network:
Kilobytes / sec = 46128168
Kilobytes / sec = 46128200
Kilobytes / sec = 46128152
Kilobytes / sec = 46128142
Kilobytes / sec = 46128208
Kilobytes / sec = 46128198
Kilobytes / sec = 46128202
Its interesting that the data-rate is higher with the network
plugged in and getting all those M$ broadcast messages. But, as
expected, its more stable without.
Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.
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This archive was generated by hypermail 2b29 : Sun Mar 23 2003 - 22:00:31 EST