On Fri, Mar 14, 2003 at 03:51:43PM +0000, Richard Earnshaw wrote:
> 
> This is with a kernel from yesterday and a userland from the end of 
> January...
> 
> Running time on a bootstrap of gcc on my shark now prints
> 
> real     31535.90
> user    634391.-58906
> sys    1077544.-49263
> 
> The real time is correct, but the other two are complete garbage.
> 
> What's up?

I suppose it could be related to me fixing the child times reported.
The old code did get it wrong!

try:
$ sh -c '/bin/echo;ps -Octime -p $$'
on a fast(ish) system, note that CTIMEs < 1 tick are generated.

Ahh...

Is that a bug I spotted looking at the code in calcru - but didn't fix!

It does:
	sec = p->p_rtime.tv_sec;
	usec = p->p_rtime.tv_usec;
	st = p->p_sticks;
	ut = p->p_uticks;
	it = p->p_iticks; 
	tot = st + ut + it;
	u = (u_quad_t) sec * 1000000 + usec;
	st = (u * st) / tot;
	sp->tv_sec = st / 1000000;
	sp->tv_usec = st % 1000000;

Now if real is 2^16, 'sec' is probably also 2^16,
so u = 2^16 * 2^20 = 2^36
tot ~= sec * stathz = 2^16 * 2^7 = 2^23	(for 128Hz statclok)
so u * st = 2^36 * 2^23 = 2^59

Getting all very close to 2^64...

	David

-- 
David Laight: david@l8s.co.uk