Re: udelay() possibly broken on Alpha.

H. Peter Anvin (hpa@transmeta.com)
28 Aug 1999 21:24:17 GMT


Followup to: <Pine.LNX.3.95.990828215328.940A-100000@localhost>
By author: Gerard Roudier <groudier@club-internet.fr>
In newsgroup: linux.dev.kernel
>
> Playing with this sort of alignment is not the way to go in my opinion.
> There are lots of subleties in hardware optimizations we probably never
> will know about. The difference may be due, for example, to some subtle
> hashing that takes into account some other bits.
>
> A strong alignment may allow the Bogo Mips result to be more deterministic
> among kernel actual map, but no need to have such a deterministic Bogo
> Mips result for udelay() to be accurate. It is the __delay() loop that
> must behave consistenly for udelay() to be fine.
>

I maintain that for CPUs that have a (usable) cycle counter, the
delay loop should use the cycle counter to maintain time.

-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!

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