Hi,
On Wed, 15 Jul 2020 at 12:05, Bas Nieuwenhuizen bas@basnieuwenhuizen.nl wrote:
On Wed, Jul 15, 2020 at 12:34 PM Chris Wilson chris@chris-wilson.co.uk wrote:
Maybe now is the time to ask: are you using sw_sync outside of validation?
Yes, this is used as part of the Android stack on Chrome OS (need to see if ChromeOS specific, but https://source.android.com/devices/graphics/sync#sync_timeline suggests not)
Android used to mandate it for their earlier iteration of release fences, which was an empty/future fence having no guarantee of eventual forward progress until someone committed work later on. For example, when you committed a buffer to SF, it would give you an empty 'release fence' for that buffer which would only be tied to work to signal it when you committed your _next_ buffer, which might never happen. They removed that because a) future fences were a bad idea, and b) it was only ever useful if you assumed strictly FIFO/round-robin return order which wasn't always true.
So now it's been watered down to 'use this if you don't have a hardware timeline', but why don't we work with Android people to get that removed entirely?
Cheers, Daniel