On Mon, Jul 05, 2021 at 02:48:23PM +0300, Joonas Lahtinen wrote:
Quoting Daniel Vetter (2021-07-02 23:17:08)
We're not consistently recommending these for developers only.
I stumbled over this due to DRM_I915_LOW_LEVEL_TRACEPOINTS, which was added in
commit 354d036fcf70654cff2e2cbdda54a835d219b9d2 Author: Tvrtko Ursulin tvrtko.ursulin@intel.com Date: Tue Feb 21 11:01:42 2017 +0000
drm/i915/tracepoints: Add request submit and execute tracepointsto "alleviate the performance impact concerns."
Which is nonsense.
I think that was the original reason why the patch was developed and it got merged primarily for the latter reason. Unfortunately the patch commit messages don't always get rewritten.
Tvrtko and Joonas pointed out on irc that the real (but undocumented reason) was stable abi concerns for tracepoints, see
https://lwn.net/Articles/705270/
and the specific change that was blocked around tracepoints:
https://lwn.net/Articles/442113/
Anyway to make it a notch clearer why we have this Kconfig option consistly add the "Recommended for driver developers only." to it and all the other debug options we have.
Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Matthew Brost matthew.brost@intel.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com
Reviewed-by: Joonas Lahtinen joonas.lahtinen@linux.intel.com
Pushed to drm-intel-gt-next, thanks for taking a look. -Daniel
Regards, Joonas
drivers/gpu/drm/i915/Kconfig.debug | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug index 2ca88072d30f..f27c0b5873f7 100644 --- a/drivers/gpu/drm/i915/Kconfig.debug +++ b/drivers/gpu/drm/i915/Kconfig.debug @@ -215,6 +215,8 @@ config DRM_I915_LOW_LEVEL_TRACEPOINTS This provides the ability to precisely monitor engine utilisation and also analyze the request dependency resolving timeline.
Recommended for driver developers only.If in doubt, say "N".config DRM_I915_DEBUG_VBLANK_EVADE @@ -228,6 +230,8 @@ config DRM_I915_DEBUG_VBLANK_EVADE is exceeded, even if there isn't an actual risk of missing the vblank.
Recommended for driver developers only.If in doubt, say "N".config DRM_I915_DEBUG_RUNTIME_PM @@ -240,4 +244,6 @@ config DRM_I915_DEBUG_RUNTIME_PM runtime PM functionality. This may introduce overhead during driver loading, suspend and resume operations.
Recommended for driver developers only.If in doubt, say "N"-- 2.32.0.rc2