On Jun 23, 2008, at 3:17 PM, Brian W. Barrett wrote:
Just because it's volatile doesn't mean that adds are atomic.
There's at least one place in the PML (or used to be) where two
threads could decrement that counter at the same time.
With atomics, then both subtracts should occur, right? So a request
could go from ACTIVE -> INACTIVE -> INVALID. Is that what is
desired? (I honestly don't know enough about ob1 to say)
Or should we just be assigning a specific state, rather than relying
on subtracting? That was my real question.
On Mon, 23 Jun 2008, Jeff Squyres wrote:
I see in a few places in ob1 we do things like this:
OPAL_THREAD_ADD32(&sendreq->req_state, -1);
Why do we do this? req_state is technically an enum value, so we
shouldn't be adding/subtracting to it (granted, it looks like the
enum values were carefully chosen to allow this). Additionally,
req_state is volatile; the atomics shouldn't be necessary.
Is there some other non-obvious reason?
Also, I see this in a few places:
req->req_state = 2;
which really should be
req->req_state = OMPI_REQUEST_ACTIVE;
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Jeff Squyres
Cisco Systems
