Date: Tue, 1 May 2001 11:17:54 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Rolf Neugebauer <neugebar@dcs.gla.ac.uk> Cc: freebsd-alpha@FreeBSD.ORG Subject: Re: determine cycle counter frequency in user space Message-ID: <15086.54178.150721.633298@grasshopper.cs.duke.edu> In-Reply-To: <ysqpudt9yus.fsf@therese.dcs.gla.ac.uk> References: <200104302147.OAA12404@usr01.primenet.com> <ysqpudt9yus.fsf@therese.dcs.gla.ac.uk>
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Rolf Neugebauer writes:
>
> However, to get an estimate for cycles per second, I was looking for a
> programmatic way to access above mentioned variables instead of
> providing them as command line arguments. I'll just add an appropriate
> sysctl to get cycles_per_sec. If people are interested, I'll submit a
> patch.
Depending on how accurate you needed them to be, you might be able to
just calculate them.
__inline int
GetClockCycleFreq(void)
{
unsigned long t0, t1;
int delta_t = -1;
do {
/* loop to avoid nasty negative cycle counts.. */
t0 = alpha_rpcc();
sleep(1);
t1 = alpha_rpcc();
delta_t = t1 - t0;
} while (delta_t < 0);
return(delta_t);
}
Drew
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