Date: Mon, 4 May 1998 15:51:23 +0800 From: Joerg Micheel <joerg@krdl.org.sg> To: Greg Lehey <grog@lemis.com> Cc: John-Mark Gurney <gurney_j@resnet.uoregon.edu>, FreeBSD Hackers <hackers@FreeBSD.ORG> Subject: Re: Context switch time Message-ID: <19980504155123.20764@krdl.org.sg> In-Reply-To: <19980504171054.X4777@freebie.lemis.com>; from Greg Lehey on Mon, May 04, 1998 at 05:10:54PM %2B0930 References: <Pine.BSF.3.96.980425041329.28708A-100000@fledge.watson.org> <19980425034313.55993@hydrogen.nike.efn.org> <19980504143736.L4777@freebie.lemis.com> <19980503222303.36966@hydrogen.nike.efn.org> <19980504140442.52763@krdl.org.sg> <19980504155242.P4777@freebie.lemis.com> <19980504152056.47011@krdl.org.sg> <19980504171054.X4777@freebie.lemis.com>
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On Mon, May 04, 1998 at 05:10:54PM +0930, Greg Lehey wrote:
> On Mon, 4 May 1998 at 15:20:56 +0800, Joerg Micheel wrote:
>
> Hmm, interesting, it's called getpid.c, but it calls getuid :-)
Ha! That's the bottleneck! :-)))).
Ok. Just for completeness sake:
The initial test program obviously was:
# include <unistd.h>
void
main()
{
for(;;)
(void)getpid();
}
which has been converted to:
# include <stdio.h>
# include <unistd.h>
# include <sys/time.h>
void
main()
{
int loop = 1000000;
long long total; /* in usecs */
while(loop--) {
gettimeofday(&start, NULL);
while(loop--)
(void)getpid();
gettimeofday(&stop, NULL);
}
total = ((long long)stop.tv_sec * 1000000 + (long long)stop.tv_usec)
- ((long long)start.tv_sec * 1000000 + (long long)start.tv_usec);
printf("%qd\n", total);
}
I just put another loop around it and computed the calls/sec in the
latest version.
> Hmmm. This suggests to me that we're hitting some other limit.
Joerg
--
Joerg B. Micheel Email: <joerg@krdl.org.sg>
SingAREN Technology Center Phone: +65 7705577
Kent Ridge Digital Labs Fax: +65 7795966
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