* [PATCH 0/2] drm: 2 quick fixes
@ 2026-09-26 22:33 ` Jim Cromie via B4 Relay
0 siblings, 0 replies; 6+ messages in thread
From: Jim Cromie @ 2026-09-26 22:33 UTC (permalink / raw)
To: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter
Cc: dri-devel, linux-kernel, Jim Cromie
1. make __drm_debug __read_mostly
it is rarely written, and read at up to 80khz
2. fix CFLAGS -> ccflags mis-spelling
this fails to add -DDYNAMIC_DEBUG_MODULE to ccflags
currently masked by DRM_USE_DYNAMIC_DEBUG=n
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
Jim Cromie (2):
drm/print: Mark __drm_debug as __read_mostly
drm: Fix incorrect ccflags-y spelling inside Makefile
drivers/gpu/drm/Makefile | 3 ++-
drivers/gpu/drm/drm_print.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
---
base-commit: 93f51579e7df248780214094418f205253383cc5
change-id: 20260925-rd-mostly-6a2fc0cd6fd6
Best regards,
--
Jim Cromie <jim.cromie@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 0/2] drm: 2 quick fixes
@ 2026-09-26 22:33 ` Jim Cromie via B4 Relay
0 siblings, 0 replies; 6+ messages in thread
From: Jim Cromie via B4 Relay @ 2026-09-26 22:33 UTC (permalink / raw)
To: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter
Cc: dri-devel, linux-kernel, Jim Cromie
1. make __drm_debug __read_mostly
it is rarely written, and read at up to 80khz
2. fix CFLAGS -> ccflags mis-spelling
this fails to add -DDYNAMIC_DEBUG_MODULE to ccflags
currently masked by DRM_USE_DYNAMIC_DEBUG=n
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
Jim Cromie (2):
drm/print: Mark __drm_debug as __read_mostly
drm: Fix incorrect ccflags-y spelling inside Makefile
drivers/gpu/drm/Makefile | 3 ++-
drivers/gpu/drm/drm_print.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
---
base-commit: 93f51579e7df248780214094418f205253383cc5
change-id: 20260925-rd-mostly-6a2fc0cd6fd6
Best regards,
--
Jim Cromie <jim.cromie@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] drm/print: Mark __drm_debug as __read_mostly
2026-09-26 22:33 ` Jim Cromie via B4 Relay
@ 2026-09-26 22:33 ` Jim Cromie via B4 Relay
-1 siblings, 0 replies; 6+ messages in thread
From: Jim Cromie @ 2026-09-26 22:33 UTC (permalink / raw)
To: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter
Cc: dri-devel, linux-kernel, Jim Cromie
Under a multi-client workload of 12 concurrent vkcubes on AMD iGPU,
__drm_debug is read at ~83.3 kHz across multiple cores during atomic
and vblank checks.
__drm_debug is written only when userspace does:
echo 0xff > /sys/module/drm/parameters/debug
Currently the linker packs __drm_debug into .bss adjacent to hot
structures: drm_lease_idr_object, drm_class, and drm_global_mutex,
causing unnecessary cacheline invalidations.
Mark __drm_debug as __read_mostly to relocate it to .data..read_mostly.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
drivers/gpu/drm/drm_print.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 86cef1a37678..50cdeb1b15e2 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -40,7 +40,7 @@
* __drm_debug: Enable debug output.
* Bitmask of DRM_UT_x. See include/drm/drm_print.h for details.
*/
-unsigned long __drm_debug;
+unsigned long __drm_debug __read_mostly;
EXPORT_SYMBOL(__drm_debug);
MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
--
2.55.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 1/2] drm/print: Mark __drm_debug as __read_mostly
@ 2026-09-26 22:33 ` Jim Cromie via B4 Relay
0 siblings, 0 replies; 6+ messages in thread
From: Jim Cromie via B4 Relay @ 2026-09-26 22:33 UTC (permalink / raw)
To: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter
Cc: dri-devel, linux-kernel, Jim Cromie
From: Jim Cromie <jim.cromie@gmail.com>
Under a multi-client workload of 12 concurrent vkcubes on AMD iGPU,
__drm_debug is read at ~83.3 kHz across multiple cores during atomic
and vblank checks.
__drm_debug is written only when userspace does:
echo 0xff > /sys/module/drm/parameters/debug
Currently the linker packs __drm_debug into .bss adjacent to hot
structures: drm_lease_idr_object, drm_class, and drm_global_mutex,
causing unnecessary cacheline invalidations.
Mark __drm_debug as __read_mostly to relocate it to .data..read_mostly.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
drivers/gpu/drm/drm_print.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 86cef1a37678..50cdeb1b15e2 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -40,7 +40,7 @@
* __drm_debug: Enable debug output.
* Bitmask of DRM_UT_x. See include/drm/drm_print.h for details.
*/
-unsigned long __drm_debug;
+unsigned long __drm_debug __read_mostly;
EXPORT_SYMBOL(__drm_debug);
MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
--
2.55.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] drm: Fix incorrect ccflags-y spelling inside Makefile
2026-09-26 22:33 ` Jim Cromie via B4 Relay
@ 2026-09-26 22:33 ` Jim Cromie via B4 Relay
-1 siblings, 0 replies; 6+ messages in thread
From: Jim Cromie @ 2026-09-26 22:33 UTC (permalink / raw)
To: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter
Cc: dri-devel, linux-kernel, Jim Cromie
Fix a longstanding spelling error in the DRM Makefile by changing
'CFLAGS-y' to 'ccflags-y'. This fixes CONFIG_DRM_USE_DYNAMIC_DEBUG=y
dependent addition of -DDYNAMIC_DEBUG_MODULE, which is needed to
enable dyndbg-under-drm-debug when only CONFIG_DYNAMIC_DEBUG_CORE is
enabled (and not CONFIG_DYNAMIC_DEBUG itself).
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
drivers/gpu/drm/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index e635fcffd379..c42884d84ad1 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -3,7 +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-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
+ccflags-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
+subdir-ccflags-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
# Unconditionally enable W=1 warnings locally
# --- begin copy-paste W=1 warnings from scripts/Makefile.warn
--
2.55.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] drm: Fix incorrect ccflags-y spelling inside Makefile
@ 2026-09-26 22:33 ` Jim Cromie via B4 Relay
0 siblings, 0 replies; 6+ messages in thread
From: Jim Cromie via B4 Relay @ 2026-09-26 22:33 UTC (permalink / raw)
To: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter
Cc: dri-devel, linux-kernel, Jim Cromie
From: Jim Cromie <jim.cromie@gmail.com>
Fix a longstanding spelling error in the DRM Makefile by changing
'CFLAGS-y' to 'ccflags-y'. This fixes CONFIG_DRM_USE_DYNAMIC_DEBUG=y
dependent addition of -DDYNAMIC_DEBUG_MODULE, which is needed to
enable dyndbg-under-drm-debug when only CONFIG_DYNAMIC_DEBUG_CORE is
enabled (and not CONFIG_DYNAMIC_DEBUG itself).
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
drivers/gpu/drm/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index e635fcffd379..c42884d84ad1 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -3,7 +3,8 @@
# Makefile for the drm device driver. This driver provides support for the
# Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
-CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
+ccflags-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
+subdir-ccflags-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
# Unconditionally enable W=1 warnings locally
# --- begin copy-paste W=1 warnings from scripts/Makefile.warn
--
2.55.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-09-26 22:34 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2026-09-26 22:33 [PATCH 0/2] drm: 2 quick fixes Jim Cromie
2026-09-26 22:33 ` Jim Cromie via B4 Relay
2026-09-26 22:33 ` [PATCH 1/2] drm/print: Mark __drm_debug as __read_mostly Jim Cromie
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2026-09-26 22:33 ` [PATCH 2/2] drm: Fix incorrect ccflags-y spelling inside Makefile Jim Cromie
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