[Intel-gfx] [PATCH i-g-t] tests/vgem_basic: Retry the initial module unload in unload test

[Daniel Vetter]

On Tue, Oct 18, 2016 at 01:48:52PM +0100, Chris Wilson wrote:
> On Tue, Oct 18, 2016 at 03:41:54PM +0300, Petri Latvala wrote:
> > How should vgem work be flushed properly? With this i915 flushing is
> > guaranteed even if vgem is opened first, then i915, but such
> > flushing won't be done if only vgem is opened (I see only vgem_slow
> > doing that)...
> 
> vgem doesn't have the same delayed close as i915. For vgem, closing the
> fd (i.e. on process exit) will first signal all fences and drop
> references for that fd, so effectively all work will be completed. The
> external references to the vgem.ko's object (via dma-buf) will only
> exist if they were constructed by the test and if they were, e.g. i915,
> they too should be will be flushed by igt in its exithandlers.
> 
> Other drivers may have similar bridges to cross ofc.

One long-term caveat is that exit handlers only run on final exit, not
after each subtest. Atm that's no issue because we run each subtest in
isolation. But I think that for throughput reasons (some of the testcases
run _much_ faster if you just launch the binary once, due to fairly heavy
overhead in igt_fixtures) we can't rely on that forever.

Mostly thinking of high-throughput complete test runs here.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch