BCS wrote:
Reply to Andrei,
BCS wrote:
Everything is indicating that shared memory multi-threading is where
it's all going.
That is correct, just that it's 40 years late. Right now everything is
indicating that things are moving *away* from shared memory.
Andrei
I'm talking at the ASM level (not the language model level) and as
opposed to each thread running in its own totally isolated address space.
Am I wrong in assuming that most languages use user mode (not kernel
mode) shared memory for inter thread communication?
What happens is that memory is less shared as cache hierarchies go
deeper. It was a great model when there were a couple of processors
hitting on the same memory because it was close to reality. Cache
hierarchies reveal the hard reality that memory is shared to a
decreasing extent and that each processor would rather deal with its own
memory. Incidentally, message-passing-style protocols are prevalent in
such architectures even at low level. It follows that message passing is
not only an attractive model for programming at large, but also a model
that's closer to machine than memory sharing.
Andrei
