On 06/13/2011 05:39 PM, Kent Borg wrote:
> I was assuming that drivers, responding to an interrupt from some
> external event, would want to make this call.
> Such as a network driver.
Those already are doing this.
> Two points:
>
> 1. Why look at the high-order bits? How are they going to have values
> that cannot be inferred? If you are looking for entropy, the low-order
> bits is where they're going keep it. (Think Willie Sutton.) If looking
> at the low-byte is cheaper, then let's be cheap. If, however, if
> looking at more bytes *is* as cheap, then there is no harm. But in any
> case let's keep the code lean enough that it can be called from an
> interrupt service routine.
Consider the case where the TSC is running in steps of 64 and you're
using the low 6 bits.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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