Re: [PATCH 6/24] make atomic_read() behave consistently on frv

Nick Piggin
2007-08-16T01:21:19Z

Segher Boessenkool wrote:
>> Please check the definition of "cache coherence".
>
>
> Which of the twelve thousand such definitions? :-)

Every definition I have seen says that writes to a single memory
location have a serial order as seen by all CPUs, and that a read
will return the most recent write in the sequence (with a bit of
extra mumbo jumbo to cover store queues and store forwarding).

Within such a definition, I don't see how would be allowed for a
single CPU to execute reads out of order and have the second read
return an earlier write than the first read.

--
SUSE Labs, Novell Inc.