On Sat, Oct 08, 2016 at 09:23:25AM +0100, Tvrtko Ursulin wrote: > > On 07/10/2016 17:37, Chris Wilson wrote: > >On Fri, Oct 07, 2016 at 05:16:17PM +0100, Tvrtko Ursulin wrote: > >>On 07/10/2016 17:12, Chris Wilson wrote: > >>>>2. Can child be another array? > >>>Yes, but we don't want to recurse (or at least need to bound the > >>>recursion). > >>In that case could the array have been created in the signal_on_any > >>mode and how would we handle that? > >Hmm. Not along our paths, I think. The only fence-array we have are from > >sync-file which are signal-on-all (except... in the case of where it > >wraps a single fence, that fence could be a composite). signal-on-any is > >icky, to be complete we should not decompose it into its elements - > >however, whether or not a fence-array is operating in signal_on_any mode > >is not stored. So at the moment, the best I can do is offer a comment. > > Yes signal-on-any sounds extremely weird. It mandates you decompose > 3rd party fences in all cases, with recursion. > > >The only user of it at the moment is amdgpu waiting for the first of > >many VM manager to become available, not something we'll see > >immediately via sync-file. > > So userspace cannot engineer it to happen with some funky operations > before giving us a fence? No. sync_file is a fence-array (in normal signal-on-all mode) or a single fence (which via merging sync_files can not be another fence-array, though the sync_file could be constructed pointing to a single fence-array fence). If that is a signal-on-any fence, it is broken if the sync_file is ever merged.... And reviewing the existing code, no one should be creating sync_file from a signal-on-any fence-array. There is no ABI to allow the user to create signal-on-any sync_file. I'm feeling safer that there are quite a few issues to resolve before signal-on-any fences are allowed to pollute the sync_file ABI. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
