Limit row-mt threads based on tile size for encoder
As per theoretical estimate, in case of encoder row-mt,
Maximum number of threads allowed for a tile should be:
MIN(Num_of_SB_cols/2,Num_of_SB_rows).
In row based multi-threading of encoder, this patch limits
the number of threads assigned to a tile as per theoretical
limits.
Change-Id: I360147a2648460a3e5b8d6acb45a149be429a096
diff --git a/av1/encoder/ethread.c b/av1/encoder/ethread.c
index 77fb811..5374053 100644
--- a/av1/encoder/ethread.c
+++ b/av1/encoder/ethread.c
@@ -236,26 +236,30 @@
int tile_index = tile_row * tile_cols + tile_col;
TileDataEnc *this_tile = &cpi->tile_data[tile_index];
AV1RowMTInfo *row_mt_info = &this_tile->row_mt_info;
- int num_mis_to_encode =
- this_tile->tile_info.mi_row_end - row_mt_info->current_mi_row;
+ int theoretical_limit_on_threads = (int)(round(AOMMAX(
+ (double)(av1_get_sb_cols_in_tile(cm, this_tile->tile_info)) / 2, 1)));
+ int num_threads_working = row_mt_info->num_threads_working;
+ if (num_threads_working < theoretical_limit_on_threads) {
+ int num_mis_to_encode =
+ this_tile->tile_info.mi_row_end - row_mt_info->current_mi_row;
- // Tile to be processed by this thread is selected on the basis of
- // availability of jobs:
- // 1) If jobs are available, tile to be processed is chosen on the
- // basis of minimum number of threads working for that tile. If two or
- // more tiles have same number of threads working for them, then the tile
- // with maximum number of jobs available will be chosen.
- // 2) If no jobs are available, then end_of_frame is reached.
- if (num_mis_to_encode > 0) {
- int num_threads_working = row_mt_info->num_threads_working;
- if (num_threads_working < min_num_threads_working) {
- min_num_threads_working = num_threads_working;
- max_mis_to_encode = 0;
- }
- if (num_threads_working == min_num_threads_working &&
- num_mis_to_encode > max_mis_to_encode) {
- tile_id = tile_index;
- max_mis_to_encode = num_mis_to_encode;
+ // Tile to be processed by this thread is selected on the basis of
+ // availability of jobs:
+ // 1) If jobs are available, tile to be processed is chosen on the
+ // basis of minimum number of threads working for that tile. If two or
+ // more tiles have same number of threads working for them, then the
+ // tile with maximum number of jobs available will be chosen.
+ // 2) If no jobs are available, then end_of_frame is reached.
+ if (num_mis_to_encode > 0) {
+ if (num_threads_working < min_num_threads_working) {
+ min_num_threads_working = num_threads_working;
+ max_mis_to_encode = 0;
+ }
+ if (num_threads_working == min_num_threads_working &&
+ num_mis_to_encode > max_mis_to_encode) {
+ tile_id = tile_index;
+ max_mis_to_encode = num_mis_to_encode;
+ }
}
}
}
@@ -616,7 +620,7 @@
const int tile_rows = cm->tile_rows;
MultiThreadHandle *multi_thread_ctxt = &cpi->multi_thread_ctxt;
int num_workers = 0;
- int total_num_sb_rows = 0;
+ int total_num_threads_row_mt = 0;
int max_sb_rows = 0;
if (cpi->tile_data == NULL || cpi->allocated_tiles < tile_cols * tile_rows) {
@@ -631,11 +635,19 @@
TileDataEnc *tile_data = &cpi->tile_data[row * cm->tile_cols + col];
int num_sb_rows_in_tile =
av1_get_sb_rows_in_tile(cm, tile_data->tile_info);
- total_num_sb_rows += num_sb_rows_in_tile;
+ int num_sb_cols_in_tile =
+ av1_get_sb_cols_in_tile(cm, tile_data->tile_info);
+ total_num_threads_row_mt += (int)round(AOMMIN(
+ AOMMAX((double)(num_sb_cols_in_tile) / 2, 1), num_sb_rows_in_tile));
max_sb_rows = AOMMAX(max_sb_rows, num_sb_rows_in_tile);
}
}
- num_workers = AOMMIN(cpi->oxcf.max_threads, total_num_sb_rows);
+ // TODO(ravi.chaudhary@ittiam.com): Currently the percentage of
+ // post-processing stages in encoder is quiet low, so limiting the number of
+ // threads to the theoretical limit in row-mt does not have much impact on
+ // post-processing multi-threading stage. Need to revisit this when
+ // post-processing time starts shooting up.
+ num_workers = AOMMIN(cpi->oxcf.max_threads, total_num_threads_row_mt);
if (multi_thread_ctxt->allocated_tile_cols != tile_cols ||
multi_thread_ctxt->allocated_tile_rows != tile_rows ||
