[Bf-blender-cvs] [ef6ce4fa8ca] cycles-x: Cycles X: More flexible tile scheduling support

[Sergey Sharybin]

Commit: ef6ce4fa8ca652cf729dbb7d7002dd37391e3898
Author: Sergey Sharybin
Date:   Wed May 19 16:09:14 2021 +0200
Branches: cycles-x
https://developer.blender.org/rBef6ce4fa8ca652cf729dbb7d7002dd37391e3898

Cycles X: More flexible tile scheduling support

Allow tiles with sample range smaller than the currently rendering
number of samples.

The previous code was trying to support it already, but it had some
mistakes in the math.

Currently should be no functional changes.

===================================================================

M	intern/cycles/integrator/work_tile_scheduler.cpp
M	intern/cycles/integrator/work_tile_scheduler.h

===================================================================

diff --git a/intern/cycles/integrator/work_tile_scheduler.cpp b/intern/cycles/integrator/work_tile_scheduler.cpp
index 2d9541852ae..6557b470164 100644
--- a/intern/cycles/integrator/work_tile_scheduler.cpp
+++ b/intern/cycles/integrator/work_tile_scheduler.cpp
@@ -72,23 +72,25 @@ void WorkTileScheduler::reset_scheduler_state()
   num_tiles_y_ = divide_up(image_size_px_.y, tile_size_.height);
 
   total_tiles_num_ = num_tiles_x_ * num_tiles_y_;
+  num_tiles_per_sample_range_ = divide_up(samples_num_, tile_size_.num_samples);
 
   next_work_index_ = 0;
-  total_work_size_ = total_tiles_num_ *
-                     static_cast<int>(ceilf(samples_num_ / tile_size_.num_samples));
+  total_work_size_ = total_tiles_num_ * num_tiles_per_sample_range_;
 }
 
 bool WorkTileScheduler::get_work(KernelWorkTile *work_tile_, const int max_work_size)
 {
   DCHECK_NE(max_num_path_states_, 0);
+  DCHECK_LE(max_work_size, max_num_path_states_);
 
   const int work_index = atomic_fetch_and_add_int32(&next_work_index_, 1);
   if (work_index >= total_work_size_) {
     return false;
   }
 
-  const int sample = work_index / total_tiles_num_;
-  const int tile_index = work_index - sample * total_tiles_num_;
+  const int sample_range_index = work_index / total_tiles_num_;
+  const int start_sample = sample_range_index * tile_size_.num_samples;
+  const int tile_index = work_index - sample_range_index * total_tiles_num_;
   const int tile_y = tile_index / num_tiles_x_;
   const int tile_x = tile_index - tile_y * num_tiles_x_;
 
@@ -97,8 +99,8 @@ bool WorkTileScheduler::get_work(KernelWorkTile *work_tile_, const int max_work_
   work_tile.y = tile_y * tile_size_.height;
   work_tile.w = tile_size_.width;
   work_tile.h = tile_size_.height;
-  work_tile.start_sample = sample_start_ + sample;
-  work_tile.num_samples = tile_size_.num_samples;
+  work_tile.start_sample = sample_start_ + start_sample;
+  work_tile.num_samples = min(tile_size_.num_samples, samples_num_ - start_sample);
   work_tile.offset = offset_;
   work_tile.stride = stride_;
 
@@ -108,8 +110,11 @@ bool WorkTileScheduler::get_work(KernelWorkTile *work_tile_, const int max_work_
   work_tile.x += image_full_offset_px_.x;
   work_tile.y += image_full_offset_px_.y;
 
-  DCHECK_LE(max_work_size, max_num_path_states_);
-  if (max_work_size && work_tile.w * work_tile.h * work_tile.num_samples > max_work_size) {
+  const int tile_work_size = work_tile.w * work_tile.h * work_tile.num_samples;
+
+  DCHECK_GT(tile_work_size, 0);
+
+  if (max_work_size && tile_work_size > max_work_size) {
     /* The work did not fit into the requested limit of the work size. Unschedule the tile,
      * allowing others (or ourselves later one) to pick it up.
      *
diff --git a/intern/cycles/integrator/work_tile_scheduler.h b/intern/cycles/integrator/work_tile_scheduler.h
index d8840922252..1c70f4554bc 100644
--- a/intern/cycles/integrator/work_tile_scheduler.h
+++ b/intern/cycles/integrator/work_tile_scheduler.h
@@ -87,6 +87,10 @@ class WorkTileScheduler {
    * in the `get_work()`? */
   int total_tiles_num_ = 0;
 
+  /* In the case when the number of sam[les in the `tile_size_` is lower than samples_num_ denotes
+   * how many tiles are to be "stacked" to cover the entire requested range of samples. */
+  int num_tiles_per_sample_range_ = 0;
+
   int next_work_index_ = 0;
   int total_work_size_ = 0;
 };