Mesa (master): radeon/winsys: Limit max allocation size to 70% of VRAM

[Aaron Watry]

Module: Mesa
Branch: master
Commit: e4d06e4c531157f1f3e4683487ee9c81fa0cff9b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=e4d06e4c531157f1f3e4683487ee9c81fa0cff9b

Author: Aaron Watry <awatry at gmail.com>
Date:   Fri Jun  9 12:57:42 2017 -0500

radeon/winsys: Limit max allocation size to 70% of VRAM

The CL CTS queries the max allocation size, and then attempts to
allocate buffers of that size. If not enough contiguous RAM/VRAM is
available, this causes errors in the radeon kernel module due to
inability to allocate the required memory.

It's a bit of a hack, but experimentally on my system, I can use ~3/4
of the card's VRAM for a single global/constant buffer allocation given
current GUI/compositor use.

For a 1GB Pitcairn (HD7850) this gets me from the reported clinfo values of:
Global memory size                              2143076352 (1.996GiB)
Max memory allocation                           1500153446 (1.397GiB)
Max constant buffer size                        1500153446 (1.397GiB)

To:
Global memory size                              2143076352 (1.996GiB)
Max memory allocation                           751619276 (716MiB)
Max constant buffer size                        751619276 (716MiB)

Fixes: OpenCL CTS test/conformance/api/min_max_mem_alloc_size,
       OpenCL CTS test/conformance/api/min_max_constant_buffer_size

Signed-off-by: Aaron Watry <awatry at gmail.com>
Reviewed-by: Marek Olšák <marek.olsak at amd.com>

---

 src/gallium/winsys/radeon/drm/radeon_drm_winsys.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c b/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
index 9bbffa514a..e0d4cc8d77 100644
--- a/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
+++ b/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
@@ -365,6 +365,8 @@ static bool do_winsys_init(struct radeon_drm_winsys *ws)
     /* Radeon allocates all buffers as contigous, which makes large allocations
      * unlikely to succeed. */
     ws->info.max_alloc_size = MAX2(ws->info.vram_size, ws->info.gart_size) * 0.7;
+    if (ws->info.has_dedicated_vram)
+        ws->info.max_alloc_size = MIN2(ws->info.vram_size * 0.7, ws->info.max_alloc_size);
     if (ws->info.drm_minor < 40)
         ws->info.max_alloc_size = MIN2(ws->info.max_alloc_size, 256*1024*1024);