On 11-12-07 15:15, Rene Herman wrote:

> On 11-12-07 14:32, Paul Rolland wrote:
> 
>>> On 11-12-07 13:08, David Newall wrote:
>>>
>>>> Rene Herman wrote:
>>
>>> (*) some local testing shows it to be almost exactly that for both 
>>> out and in on my own PC -- a little over. If anyone cares, see 
>>> attached little test program. The "little over" I don't worry about. 
>>> 0 us delay is also fine for me and if any code was _that_ fragile it 
>>> would have broken long ago.
>>
>> Some results :
> 
> Okay, these vary to wildly for you and might I suppose be a serialising 
> artifact or some such. Give me a bit and I'll try to improve it...

This might be a bit more constant, I suppose. This serialises with cpuid. 
Don't see a difference locally, but perhaps you do.

On a Duron 1300 with an actual ISA bus, "out" is between 1300 and 1600 for 
me and "in" between 1200 and 1500 with a few flukes above that which will I 
suppose be caused by the bus (ISA _or_ PCI) being momentarily busy or some 
such...

Rene.