Date: Thu, 30 Aug 2001 09:41:48 EDT From: Bsdguru@aol.com To: mb@imp.ch Cc: hackers@freebsd.org Subject: Re: Clock speedup on 4.X FreeBSD SMP and serverworks chipset Message-ID: <14b.2a17a2.28bf9c9c@aol.com>
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In a message dated 8/30/01 7:44:23 AM Eastern Daylight Time, mb@imp.ch writes:
> Searching the freebsd mailinglists I have seen that you also suffering
> under this problem on 4.X. STABLE:
>
> I have isolated the problem to be due reading the time with microtime()
>
> Execute this programm:
>
> #include <sys/types.h>
> #include <sys/time.h>
> #include <err.h>
>
> int
> main(void)
> {
>
> for(;;) {
> struct timeval tv;
> struct timezone tz;
> gettimeofday(&tv, &tz);
> }
> return (0);
> }
>
> and you will see a 10% timedrift. For 20 seconds, I get 2 second
> time speedup.
>
> You should not see this time drift if you remove the gettimeofday()
> syscall of the programm.
>
> If someone has a machine where he can install CURRENT, or has a machine
> with ServerWorks Chipset and SMP, is it possible that he can activate
> ACPI and test it again ?
>
> There is already a PR, PR kern/30135.
>
maybe the millions of system calls to the time function has something to do
with the effect?
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