[igt-dev] [PATCH i-g-t v2] lib/hang_ctx: Make use of dummyload library to create recursive batch

[Chris Wilson]

Quoting Antonio Argenziano (2018-07-10 16:48:38)
> On 10/07/18 08:38, Chris Wilson wrote:
> > Quoting Antonio Argenziano (2018-07-10 16:31:55)
> > Overall I am still dubious there is any reason to set this flag. The
> > ratelimiting step here isn't the speed at which the batch spins, but the
> > time for hangcheck to kick in. Where a fast spinner is interesting is
> > the latency in responding to terminating the spinner (which never
> > happens for a hang!).
> 
> The flag makes sense to me because hangcheck will always sample the same 
> head on a very tight loop like the fast spinner. The current 
> implementation of hangcheck will also declare the engine hung much 
> quicker.

True, but I don't think much more than 1 or 2 extra ticks. In the grand
scheme of things, using the pollable spinner + manual hang injection is
far far far far far far quicker and precise.

> In general I think we should expose different hanging batch to 
> the driver to make sure it can react to the different situations.

Harder to call (where do you draw the line between meaningful and
hanging batch), but such construction is better done inside the test
than inside a general purpose library (as it is no longer general
purpose).
-Chris