summaryrefslogtreecommitdiff
path: root/src/threads.c
AgeCommit message (Collapse)Author
2017-09-14*: use fragment generatorVito Caputo
Rather than laying out all fragments in a frame up-front in ray_module_t.prepare_frame(), return a fragment generator (rototiller_fragmenter_t) which produces the numbered fragment as needed. This removes complexity from the serially-executed prepare_frame() and allows the individual fragments to be computed in parallel by the different threads. It also eliminates the need for a fragments array in the rototiller_frame_t, indeed rototiller_frame_t is eliminated altogether.
2017-08-07threads: rework threaded fragment schedulingVito Caputo
Instead of creating fragment lists striped across available threads uniformly in a round-robin fashion, just have the render threads iterate across the shared fragments array using atomics. This way non-uniform cost of rendering can be adapted to, provided the module prepares the frame with sufficient fragment granularity. In the ray tracer for example, it is quite common for some areas of the screen to have lower complexity/cost than others. The previous model distributed the fragments uniformly across the threads with no ability for underutilized threads to steal work from overutilized threads in the event of non-uniform cost distributions. Now no attempt to schedule work is made. The render threads simply race with eachother on a per-frame basis, atomically incrementing a shared index into the frame's prepared fragemnts. The fragment size itself represents the atomic work unit. A later commit will change the various renderers to prepare more/smaller fragments where appropriate. The ray tracer in particular needs more and would probably further benefit from a tiling strategy, especially when an acceleration data structure is introduced.
2017-04-22*: add module context machineryVito Caputo
introduces create_context() and destroy_context() methods, and adds a 'void *context' first parameter to the module methods. If a module doesn't supply create_context() then NULL is simply passed around as the context, so trivial modules can continue to only implement render_fragment(). A subsequent commit will update the modules to encapsulate their global state in module-specific contexts.
2017-04-22rototiller: add threaded renderingVito Caputo
This is a simple worker thread implementation derived from the ray_threads code in the ray module. The ray_threads code should be discarded in a future commit now that rototiller can render fragments using threads. If a module supplies a prepare_frame() method, then it is called per-frame to prepare a rototiller_frame_t which specifies how to divvy up the page into fragments. Those fragments are then dispatched to a thread per CPU which call the module's rendering function in parallel. There is no coupling of the number of fragments in a frame to the number of threads/CPUs. Some modules may benefit from the locality of tile-based rendering, so the fragments are simply dispatched across the available CPUs in a striped fashion. Helpers will be added later to the fb interface for tiling fragments, which modules desiring tiled rendering may utilize in their prepare_frame() methods. This commit does not modify any modules to become threaded, it only adds the scaffolding.
© All Rights Reserved