gpu: nvgpu: Fix submit profiling stat reporting

The debugfs submit profiling stats report the distribution of submit
times at different percentiles. The original code reports the lowest
entry in every percentile-bin as being representative for that
bin. This means that where debugfs reports the 50th percentile, it
actually reports the ~45.001th percentile. This is especially
inconveniant when looking at the 100th percentile, which does not in
fact reflect the maximum.

This patch changes the code to instead report the highest entry in
every percentile-bin.

Change-Id: Ibde3aaf6445e08af09a4a96156f8421cbeb8bae5
Signed-off-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Reviewed-on: http://git-master/r/1461658
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c b/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
index ad200f38..519fa509 100644
--- a/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
@@ -3626,8 +3626,8 @@ static unsigned int __gk20a_fifo_create_stats(struct gk20a *g,
         /* build ranges */
         for (index = 0; index < PERCENTILE_RANGES; index++)
                 percentiles[index] =
-                        g->fifo.profile.sorted[(PERCENTILE_WIDTH * index *
-                                                nelem)/100];
+                        g->fifo.profile.sorted[(PERCENTILE_WIDTH * (index + 1) *
+                                                nelem)/100 - 1];
         return nelem;
 }