[Mesa-dev] [PATCH 7/8] radeonsi: always put persistent buffers into GTT on radeon

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

This improves performance for certain games.

Cc: 18.1 <mesa-stable at lists.freedesktop.org>
---
 src/gallium/drivers/radeonsi/si_buffer.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/radeonsi/si_buffer.c b/src/gallium/drivers/radeonsi/si_buffer.c
index 2d68edc3404..0546fa9d336 100644
--- a/src/gallium/drivers/radeonsi/si_buffer.c
+++ b/src/gallium/drivers/radeonsi/si_buffer.c
@@ -144,22 +144,26 @@ void si_init_resource_fields(struct si_screen *sscreen,
 	if (res->b.b.target == PIPE_BUFFER &&
 	    res->b.b.flags & (PIPE_RESOURCE_FLAG_MAP_PERSISTENT |
 			      PIPE_RESOURCE_FLAG_MAP_COHERENT)) {
 		/* Use GTT for all persistent mappings with older
 		 * kernels, because they didn't always flush the HDP
 		 * cache before CS execution.
 		 *
 		 * Write-combined CPU mappings are fine, the kernel
 		 * ensures all CPU writes finish before the GPU
 		 * executes a command stream.
+		 *
+		 * radeon doesn't have good BO move throttling, so put all
+		 * persistent buffers into GTT to prevent VRAM CPU page faults.
 		 */
-		if (!sscreen->info.kernel_flushes_hdp_before_ib)
+		if (!sscreen->info.kernel_flushes_hdp_before_ib ||
+		    sscreen->info.drm_major == 2)
 			res->domains = RADEON_DOMAIN_GTT;
 	}
 
 	/* Tiled textures are unmappable. Always put them in VRAM. */
 	if ((res->b.b.target != PIPE_BUFFER && !rtex->surface.is_linear) ||
 	    res->b.b.flags & SI_RESOURCE_FLAG_UNMAPPABLE) {
 		res->domains = RADEON_DOMAIN_VRAM;
 		res->flags |= RADEON_FLAG_NO_CPU_ACCESS |
 			 RADEON_FLAG_GTT_WC;
 	}
-- 
2.17.1