On 04/12/14 16:10, Nilay Vaish via gem5-dev wrote:
I have been trying to run ht kvm cpu when using multiple cores.  With
single threaded simulation, the simulation stops making progress if the
simulated system has more than 4 cores.  With multi-threaded simulation, I
do not see any progress even when two cores are being simulated.  For the
multi-threaded simulation, I made the following changes as suggested in
the comment for the changeset:   10157:5c2ecad1a3c9.  So, how many cores
have others tested kvm cpu with?  Is there something that I might not be
doing right?

I reported scalability numbers up to 8 cores for one of the Splash 2
benchmarks in my thesis, so 8 cores definitely work. IIRC, I tested it
on 32 cores as well, but I didn't report those numbers.

There are three issues you might be running into:

 * There might be devices (CPU child objects) that don't live in the
right thread.
 * The quantum might be too large (I never managed to get anything more
than 1ms to work).
 * Newly introduced bugs.

The code fragment I used in my old scripts was something like this:

    if not no_kvm and cpus > 1:
        test_sys.eventq_index = 0
        for idx, cpu in enumerate(test_sys.cpu_boot):
            for obj in cpu.descendants():
                obj.eventq_index = test_sys.eventq_index
            cpu.eventq_index = idx + 1

The fragment above ensures that any descendants of the CPU are assigned
to the device thread and only the CPU lives in a separate thread.

//Andreas


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