[Mesa-dev] [PATCH] i965: free scratch buffers when destroying the context

Iago Toral Quiroga itoral at igalia.com
Wed Oct 1 04:55:32 PDT 2014

If scratch space is needed for a shader stage we try to reuse the last scratch
buffer bound to that stage. If we can't, we free the old scratch buffer and
allocate a new one. This means we always keep the last scratch buffer for a
particular shader stage around for the entire live span of the context.

These buffers are being reported by Valgrind as definitely lost after
destroying the OpenGL context. For example, for the geometry shader stage:

==18350== 248 bytes in 1 blocks are definitely lost in loss record 85 of 150
==18350==    at 0x4C2CC70: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==18350==    by 0xA1B35D6: drm_intel_gem_bo_alloc_internal (intel_bufmgr_gem.c:724)
==18350==    by 0xA1B383F: drm_intel_gem_bo_alloc (intel_bufmgr_gem.c:794)
==18350==    by 0xA1AEFA3: drm_intel_bo_alloc (intel_bufmgr.c:52)
==18350==    by 0x9D08E31: brw_get_scratch_bo (brw_program.c:226)
==18350==    by 0x9D2A0F2: do_gs_prog (brw_vec4_gs.c:280)
==18350==    by 0x9D2A635: brw_gs_precompile (brw_vec4_gs.c:401)
==18350==    by 0x9D14F68: brw_shader_precompile(gl_context*, gl_shader_program*) (brw_shader.cpp:76)
==18350==    by 0x9D157B8: brw_link_shader (brw_shader.cpp:269)
==18350==    by 0x9B0941E: _mesa_glsl_link_shader (ir_to_mesa.cpp:3038)
==18350==    by 0x99AE4ED: link_program (shaderapi.c:917)
==18350==    by 0x99AF365: _mesa_LinkProgram (shaderapi.c:1385)

So make sure that by the time we destroy the context we check if we have live
scratch buffers for the various stages and release them if that is the case.
 src/mesa/drivers/dri/i965/brw_context.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index ca389f8..6a7f837 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -876,6 +876,12 @@ intelDestroyContext(__DRIcontext * driContextPriv)
+   if (brw->vs.base.scratch_bo)
+      drm_intel_bo_unreference(brw->vs.base.scratch_bo);
+   if (brw->gs.base.scratch_bo)
+      drm_intel_bo_unreference(brw->gs.base.scratch_bo);
+   if (brw->wm.base.scratch_bo)
+      drm_intel_bo_unreference(brw->wm.base.scratch_bo);

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