On Thu, Mar 19, 2015 at 03:13:15PM +0000, Chris Wilson wrote:
> Pretty much an igt that compared the speed of just querying the hw
> counter vs querying with a regular vblank interrupt would be ideal for
> measuring the impact here.
ickle@crystalwell:/usr/src/intel-gpu-tools$ sudo ./tests/kms_vblank
IGT-Version: 1.10-gc15fb9e (x86_64) (Linux: 4.0.0-rc4+ x86_64)
Time to query current counter (idle): 2.217µs
Subtest query-idle: SUCCESS (1.006s)
Time to query current counter (busy): 0.244µs
Subtest query-busy: SUCCESS (1.201s
- 28.04% kms_vblank [kernel.kallsyms] [k] gen6_read32
- gen6_read32
+ 65.27% gm45_get_vblank_counter
+ 17.50% ironlake_disable_display_irq
+ 16.53% ironlake_enable_display_irq
+ 21.57% kms_vblank [kernel.kallsyms] [k] hsw_unclaimed_reg_detect.isra
+ 10.69% kms_vblank [kernel.kallsyms] [k] _raw_spin_lock_irqsave
+ 9.91% kms_vblank [kernel.kallsyms] [k] __intel_get_crtc_scanline
+ 6.66% kms_vblank [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
+ 1.34% kms_vblank [kernel.kallsyms] [k] i915_get_crtc_scanoutpos
+ 1.29% kms_vblank [kernel.kallsyms] [k] drm_wait_vblank
+ 1.27% kms_vblank [kernel.kallsyms] [k] hsw_unclaimed_reg_debug.isra.
+ 1.17% kms_vblank [kernel.kallsyms] [k] copy_user_enhanced_fast_strin
+ 1.12% kms_vblank [kernel.kallsyms] [k] drm_ioctl
+ 1.05% kms_vblank [kernel.kallsyms] [k] vblank_disable_and_save
--
Chris Wilson, Intel Open Source Technology Centre
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