Subject: RE: ci_lasttb should be u_quad_t?
To: Aymeric Vincent <>
From: Derek Godfrey <>
List: port-powerpc
Date: 01/04/2004 15:14:21
lasttb is used to calculate the difference in real time since
the last tick - it only has to be as many bits as the longest miss.
I have coded it for 64 and 32 - but it makes no diffence :-)
(as long as its unsigned arithmatic). 

Aymeric Vincent <> wrote:

>While investigating the lockups on macppc, I noticed in
>that the ci_lasttb field of struct cpu_info is a u_long.
>However, seeing how it is used in sys/arch/macppc/macppc/clock.c
>in microtime(), I suspect it should really contain the full tb and not
>just its lower bits.
>Is there a reason that I'm not seeing for keeping only the low-order
>bits? Or is it just that microtime() is not an important function and
>it can be expected to produce values going backward "very rarely"?
> Aymeric


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