On Wed, Aug 08, 2012 at 10:23:22AM +0100, Chris Wilson wrote: > Userspace tries to estimate the cost of ring switching based on whether > the GPU and GEM supports semaphores. (If we have multiple rings and no > semaphores, userspace assumes that the cost of switching rings between > batches is exorbitant and will endeavour to keep the next batch on the > active ring - as a coarse approximation to tracking both destination and > source surfaces.) Currently userspace has to guess whether semaphores > exist based on the chipset generation and the module parameter, > i915.semaphores. This is a crude and inaccurate guess as the defaults > internally depend upon other chipset features being enabled or disabled, > nor does it extend well into the future. By exporting a HAS_SEMAPHORES > parameter, we can easily query the driver and obtain an accurate answer. > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk> Sounds like something useful, applied for -next, thanks for the patch. -Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
