Jeff wrote:
Hi
I'm still having trouble switching correctly between DetailedCPU and SimpleCPU
for CMP simulation.
I seem to be flushing the pipeline correctly in the DetailedCPU. I'm doing
this by checking 4 different buffers/queues: the IQ, LSQ, DecodeQ, and
storebuffer. once these are empty, I feel that it is safe to say the pipe is
empty and also that all memory is updated for that particular CPU. the other
CPUs will likewise do the same and once all CPUs have done this, the
signalSwitched call in the Sampler can proceed to let the SimpleCPUs
takeOverFrom the Detailed CPUs.
Now the problem I'm seeing is that the ExecContexts don't really "completely"
takeOverFrom the ExecContexts tied to the previous phase's CPUs. There is a structure called
waitList in ExecContext, which seems to be only getting modified by the Tru64::* functions.
However, this structure is not "copied" when a takeOverFrom occurs. An example, is when
some context is put into a suspended state. Is this something that has not been completed yet?
Yea, unfortunately the Tru64 pthreads syscall emulation ended up turning
into a thread scheduler in m5 itself. I pulled the plug before it got
too ugly, but that's what that is for. I can see how that might cause
problems with the sampler, but can't suggest any quick fixes off the top
of my head.
It's really hard to tell between what is correct, incorrect, or not yet implemented yet.
Another thing I was wondering is if the CPU's should all be set up with
defer_registration set to True.
It seems like if I don't set this, then I end up with much more ExecContexts in the Process then the number of CPUs. Also, what I see is that if I'm currently executing Detailed mode and a thread is created, the Tru64::init_exec_context will actually try to use an ExecContext from one of the SimpleCPU's instead of the DetailedCPUs.
I believe that defer_registration should be true for all the CPUs that
you're not using at the beginning of the simulation.
anyways... i know i ask a lot of questions, but any help would be really
appreciated.
thanks
jeff
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