[igt-dev] [RFC] tests/i915/gem_exec_fence: Pre-fault objects with dependencies

[Daniele Ceraolo Spurio]

On 3/14/19 4:29 PM, Chris Wilson wrote:
> Quoting Antonio Argenziano (2019-03-14 23:22:32)
>> In the fault manager code we wait on an active object to complete before
>> servicing the fault. This meant that the object 'out' used in the test
>> could not be read until it became inactive which could not happen since
>> it is kept busy from the store queued behind the spinner (at least). The
>> bug became evident only after using the mmap_offset patches since we
>> were not faulting before.
> 
> out is using mmap_wc, it doesn't block inside the fault handler today.
> And it better had not start blocking in the future. Now for the opposite
> problem of removing the gratuitous blocking in the gtt fault handler,
> which may require some reminders to userspace that they needed to
> control sync themselves.
> -Chris
> 

The current patches for mmap_offset do wait on all types of mapping, so 
I guess we need to change that.

@Matt: I saw that there were lots of comments on that series so this 
issue might have already been pointed out, but if it hasn't please add 
it to the list ;)

Thanks,
Daniele