7400 and 7410 core versions are identical, afaik. I don't
think any 7410 core lower than version 2.0 was ever used
in any consumer machines. ymmv.
> I'm wondering if the MPC7400 is also affected.
> The MPC7400 has some significant differences.
> The pipeline length changed.
Between 7400 and 7410? That's news to me...
>>>The problem is that if any of those fall at the same
>>>time as the DEC interrupt, the CPU messes up it's
>>>internal state and you lose SRR0/SRR1, which means
>>>you can't recover from the exception.
>>
>>But the worst that happens is that you lose that
>>process, isn't it? Not all that big a problem,
>>esp. since the window in which this can happen is
>>very small.
>
> I think you'd get an infinite loop of either
> the decrementer or performance monitor. That's
> mostly fixable by checking for the condition and
> killing the affected process, but that process
> could be one of the ones built into the kernel.
That would be a problem, yes :-(
> So the use of oprofile comes down to a choice:
>
> a. Ignore the problem.
> rare crashes
As long as its rare, that's not _too_ big of a problem,
really. Just document it ;)
> b. The decrementer goes much faster for profiling.
> high overhead, awkwardness in non-time measurement
Bad idea, I think.
> c. The performance monitor is used for clock ticks.
> hard choices about sharing or frequency
I'd go for this option.
Segher
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