Re: [PATCH] drm/i915: Small display interrupt handlers tidy

Chris Wilson
2016-05-06T11:28:00Z

On Fri, May 06, 2016 at 12:07:04PM +0100, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> I have noticed some of our interrupt handlers use both dev and
> dev_priv while they could get away with only dev_priv in the
> huge majority of cases.
>
> Tidying that up had a cascading effect on changing functions
> prototypes, so relatively big churn factor, but I think it is
> for the better.
>
> For example even where changes cascade out of i915_irq.c, for
> functions prefixed with intel_, genX_ or <plat>_, it makes more
> sense to take dev_priv directly anyway.
>
> This allows us to eliminate local variables and intermixed usage
> of dev and dev_priv where only one is good enough.
>
> End result is shrinkage of both source and the resulting binary.
>
> i915.ko:
>
> - .text 000b0899
> + .text 000b0619
>
> Or if we look at the Gen8 display irq chain:
>
> -00000000000006ad t gen8_irq_handler
> +0000000000000663 t gen8_irq_handler
> -0000000000000028 T intel_opregion_asle_intr
> +0000000000000024 T intel_opregion_asle_intr
> -000000000000008c t ilk_hpd_irq_handler
> +000000000000007f t ilk_hpd_irq_handler
> -0000000000000116 T intel_check_page_flip
> +0000000000000112 T intel_check_page_flip
> -000000000000011a T intel_prepare_page_flip
> +0000000000000119 T intel_prepare_page_flip
> -0000000000000014 T intel_finish_page_flip_plane
> +0000000000000013 T intel_finish_page_flip_plane
> -0000000000000053 t hsw_pipe_crc_irq_handler
> +000000000000004c t hsw_pipe_crc_irq_handler
> -000000000000022e t cpt_irq_handler
> +0000000000000213 t cpt_irq_handler
>
> So small shrinkage but it is all fast paths so doesn't harm.
>
> Situation is similar in other interrupt handlers as well.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 2 +-
> drivers/gpu/drm/i915/i915_drv.h | 13 +-
> drivers/gpu/drm/i915/i915_irq.c | 386 ++++++++++++++++------------------
> drivers/gpu/drm/i915/intel_display.c | 33 ++-
> drivers/gpu/drm/i915/intel_drv.h | 12 +-
> drivers/gpu/drm/i915/intel_hotplug.c | 13 +-
> drivers/gpu/drm/i915/intel_opregion.c | 4 +-
> drivers/gpu/drm/i915/intel_pm.c | 33 ++-
> 8 files changed, 232 insertions(+), 264 deletions(-)

I have a similar series with almost identical impact, so from that
perspective we should be close. I found we could measure an improvement
in IRQ waiter wakeup latency (but only about ~2% so right on the noise
level) for gen6/gen7.

Patch looks good, spot checking against mine:

@@ -1617,8 +1617,7 @@ void gen6_rps_idle(struct drm_i915_private *dev_priv);
void gen6_rps_boost(struct drm_i915_private *dev_priv,
struct intel_rps_client *rps,
unsigned long submitted);
-void intel_queue_rps_boost_for_request(struct drm_device *dev,
- struct drm_i915_gem_request *req);
+void intel_queue_rps_boost_for_request(struct drm_i915_gem_request *req);

Follow up whilst waiting for CI?

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris

--
Chris Wilson, Intel Open Source Technology Centre