Date: Fri, 29 Apr 2005 15:26:34 +0400
From: "Andrew L. Neporada" <andr@dgap.mipt.ru>
To: freebsd-hackers@freebsd.org
Subject: open("/dev/cuaaX") is slow
Message-ID: <20050429112634.GA63285@nas.dgap.mipt.ru>
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Hi, hackers!
It seems that reopening /dev/cuaaX devices after close() takes exactly
3 seconds on FreeBSD 4.10 (sorry, I've no 5.x systems available at the
moment).
Here is output of attached program:
open() time: 155 us
open() time: 2995729 us
open() time: 2999811 us
open() time: 2999608 us
open() time: 2999711 us
open() time: 2999720 us
open() time: 2999713 us
open() time: 2999744 us
open() time: 2999673 us
open() time: 2999706 us
Is this 3 second delay necessary? Can I get rid of it?
Andrew.
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#include <sys/time.h>
#include <stdio.h>
#include <fcntl.h>
int
main(void) {
int fd, i;
long us;
struct timeval tv1, tv2;
for (i = 0; i < 10; i++) {
gettimeofday(&tv1, NULL);
fd = open("/dev/cuaa0", O_RDWR);
gettimeofday(&tv2, NULL);
us = (tv2.tv_sec - tv1.tv_sec) * 1000000 +
(tv2.tv_usec - tv1.tv_usec);
printf("open() time: %d us\n", us);
if (fd == -1) {
perror("open");
exit(1);
}
close(fd);
}
}
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