Status of smptests ...?

[Jiri Gaisler]

On 12/11/18 3:33 PM, Joel Sherrill wrote:
> The order in which threads are assigned to cores has changed since the
> first smp work. It used to be from 0 up, now from the highest core
> associated with a scheduler down. If that's the only difference, the
> screen is out of date.

Good to know, this is what I am seeing.

>
> Even if the screen is a guide of what to expect in some cases.
>
> How does the smp support in sis switch back and forth between the
> cores? Per cycle, instruction, etc. Qemu switches per instruction
> translation block as I recall.

The scheduling slice is (dynamically) configurable in number of clock
cycles. I currently have it set to 50 but the smp tests works also at
1000. The scheduling overhead is ~ 10% at 50 cycles, so the slowdown is
acceptable even for non-smp loads. My plan is to simulate each cpu
instance in a separate host thread, and synchronize them on events in
the event queue. Not quite sure how well that will work though ... :-)


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