DRM.debug API is used thousands of times in drivers/gpu/drm/*; when these are implemented using dynamic-debug, DYNAMIC_DEBUG_METADATA adds a struct _ddebug (56 bytes) per site.
Since i915 will have ~2k callsites, and amdgpu ~4k, the memory costs are substantial, and thus made configurable.
For a baseline: bash-5.1# drms_load [ 10.923093] dyndbg: 1 debug prints in module drm [ 10.928345] ACPI: bus type drm_connector registered [ 11.034012] dyndbg: 2 debug prints in module ttm [ 11.038188] dyndbg: 8 debug prints in module video [ 11.551064] dyndbg: 127 debug prints in module i915 [ 11.617106] AMD-Vi: AMD IOMMUv2 functionality not available on this system - This is not a bug. [ 12.084856] dyndbg: 2196 debug prints in module amdgpu [ 12.099040] [drm] amdgpu kernel modesetting enabled. [ 12.099790] amdgpu: CRAT table not found [ 12.100523] amdgpu: Virtual CRAT table created for CPU [ 12.100901] amdgpu: Topology: Add CPU node [ 12.165382] dyndbg: 3 debug prints in module wmi [ 12.356424] dyndbg: 3 debug prints in module nouveau
i915/gvt has pr_debugs that show up here amdgpu has many pr_debugs from macro expansions
Signed-off-by: Jim Cromie jim.cromie@gmail.com
fixup-mk --- drivers/gpu/drm/Kconfig | 12 ++++++++++++ drivers/gpu/drm/Makefile | 2 ++ 2 files changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 0039df26854b..4e7b865c3441 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -62,6 +62,18 @@ config DRM_DEBUG_MM
If in doubt, say "N".
+config DRM_USE_DYNAMIC_DEBUG + bool "use dynamic debug to implement drm.debug" + default y + depends on DRM + depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE + depends on JUMP_LABEL + help + Use dynamic-debug to avoid drm_debug_enabled() runtime overheads. + Due to callsite counts in DRM drivers (~4k in amdgpu) and 56 + bytes per callsite, the .data costs can be substantial, and + are therefore configurable. + config DRM_DEBUG_SELFTEST tristate "kselftests for DRM" depends on DRM diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 0dff40bb863c..60f4d7bc27eb 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -3,6 +3,8 @@ # Makefile for the drm device driver. This driver provides support for the # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
+CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE + drm-y := drm_aperture.o drm_auth.o drm_cache.o \ drm_file.o drm_gem.o drm_ioctl.o drm_irq.o \ drm_drv.o \