what's the point of rpython?

Scott David Daniels Scott.Daniels at Acm.Org
Wed Jan 21 17:19:04 CET 2009


Brendan Miller wrote:
> On Tue, Jan 20, 2009 at 10:03 PM, Paul Rubin
> <"http://phr.cx"@nospam.invalid> wrote:
>> ....  Of course I'm aware of the LOCK prefix but it slows
>> down the instruction enormously compared with a non-locked instruction.
> 
> I'm curious about that. I've been looking around for timing
> information on the lock signal, but am having some trouble finding
> them. Intuitively, given that the processor is much faster than the
> bus, and you are just waiting for processor to complete an addition or
> comparison before put the new memory value on the bus, it seems like
> there should be very little additional bus contention vs a normal add
> instruction.
The opcode cannot simply talk to its cache, it must either go directly
to off-chip memory or communicate to other processors that it (and it
alone) owns the increment target.

--Scott David Daniels
Scott.Daniels at Acm.Org



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