| Message ID | 20210702201708.2075793-1-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915: Improve debug Kconfig texts a bit | expand |
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 tracepoints > > to "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> 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 >
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 tracepoints > > > > to "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 > >
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"
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 tracepoints to "alleviate the performance impact concerns." Which is nonsense. 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> --- drivers/gpu/drm/i915/Kconfig.debug | 6 ++++++ 1 file changed, 6 insertions(+)