On Sat, Feb 14, 2015 at 06:30:29PM +0000, Damien Lespiau wrote:
> When one EU is disabled in a particular subslice, we can tune how the
> work is spread between subslices to improve EU utilization.
>
> v2: - Use a bitfield to record which subslice(s) has(have) 7 EUs. That
> will also make the machinery work if several sublices have 7 EUs.
> (Jeff Mcgee)
> - Only apply the different hashing algorithm if the slice is
> effectively unbalanced by checking there's a single subslice with
> 7 EUs. (Jeff Mcgee)
>
> v3: Fix typo in comment (Jeff Mcgee)
>
> Issue: VIZ-3845
> Cc: Jeff Mcgee <jeff.mc...@intel.com>
> Reviewed-by: Jeff Mcgee <jeff.mc...@intel.com>
> Signed-off-by: Damien Lespiau <damien.lesp...@intel.com>
Queued for -next, thanks for the patch.
-Daniel
> ---
> drivers/gpu/drm/i915/i915_dma.c | 17 ++++++++++---
> drivers/gpu/drm/i915/i915_drv.h | 2 ++
> drivers/gpu/drm/i915/i915_reg.h | 2 ++
> drivers/gpu/drm/i915/intel_ringbuffer.c | 45
> ++++++++++++++++++++++++++++++++-
> 4 files changed, 62 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 70acfe0..39164ff 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -649,13 +649,24 @@ static void intel_device_info_runtime_init(struct
> drm_device *dev)
> continue;
>
> for (ss = 0; ss < ss_max; ss++) {
> + u32 n_disabled;
> +
> if (ss_disable & (0x1 << ss))
> /* skip disabled subslice */
> continue;
>
> - info->eu_total += eu_max -
> - hweight8(eu_disable[s] >>
> - (ss * eu_max));
> + n_disabled = hweight8(eu_disable[s] >>
> + (ss * eu_max));
> +
> + /*
> + * Record which subslice(s) has(have) 7 EUs. we
> + * can tune the hash used to spread work among
> + * subslices if they are unbalanced.
> + */
> + if (eu_max - n_disabled == 7)
> + info->subslice_7eu[s] |= 1 << ss;
> +
> + info->eu_total += eu_max - n_disabled;
> }
> }
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index d910bac..5b4794b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -699,6 +699,8 @@ struct intel_device_info {
> u8 subslice_per_slice;
> u8 eu_total;
> u8 eu_per_subslice;
> + /* For each slice, which subslice(s) has(have) 7 EUs (bitfield)? */
> + u8 subslice_7eu[3];
> u8 has_slice_pg:1;
> u8 has_subslice_pg:1;
> u8 has_eu_pg:1;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 40f71bd..0aa6437 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1341,6 +1341,8 @@ enum skl_disp_power_wells {
> #define GEN6_WIZ_HASHING_16x4
> GEN6_WIZ_HASHING(1, 0)
> #define GEN6_WIZ_HASHING_MASK
> GEN6_WIZ_HASHING(1, 1)
> #define GEN6_TD_FOUR_ROW_DISPATCH_DISABLE (1 << 5)
> +#define GEN9_IZ_HASHING_MASK(slice) (0x3 << (slice
> * 2))
> +#define GEN9_IZ_HASHING(slice, val) ((val) <<
> (slice * 2))
>
> #define GFX_MODE 0x02520
> #define GFX_MODE_GEN7 0x0229c
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c
> b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 443e19c..c24d856 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -937,6 +937,49 @@ static int gen9_init_workarounds(struct intel_engine_cs
> *ring)
> return 0;
> }
>
> +static int skl_tune_iz_hashing(struct intel_engine_cs *ring)
> +{
> + struct drm_device *dev = ring->dev;
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + u8 vals[3] = { 0, 0, 0 };
> + unsigned int i;
> +
> + for (i = 0; i < 3; i++) {
> + u8 ss;
> +
> + /*
> + * Only consider slices where one, and only one, subslice has 7
> + * EUs
> + */
> + if (hweight8(dev_priv->info.subslice_7eu[i]) != 1)
> + continue;
> +
> + /*
> + * subslice_7eu[i] != 0 (because of the check above) and
> + * ss_max == 4 (maximum number of subslices possible per slice)
> + *
> + * -> 0 <= ss <= 3;
> + */
> + ss = ffs(dev_priv->info.subslice_7eu[i]) - 1;
> + vals[i] = 3 - ss;
> + }
> +
> + if (vals[0] == 0 && vals[1] == 0 && vals[2] == 0)
> + return 0;
> +
> + /* Tune IZ hashing. See intel_device_info_runtime_init() */
> + WA_SET_FIELD_MASKED(GEN7_GT_MODE,
> + GEN9_IZ_HASHING_MASK(2) |
> + GEN9_IZ_HASHING_MASK(1) |
> + GEN9_IZ_HASHING_MASK(0),
> + GEN9_IZ_HASHING(2, vals[2]) |
> + GEN9_IZ_HASHING(1, vals[1]) |
> + GEN9_IZ_HASHING(0, vals[0]));
> +
> + return 0;
> +}
> +
> +
> static int skl_init_workarounds(struct intel_engine_cs *ring)
> {
> struct drm_device *dev = ring->dev;
> @@ -956,7 +999,7 @@ static int skl_init_workarounds(struct intel_engine_cs
> *ring)
> HDC_FENCE_DEST_SLM_DISABLE |
> HDC_BARRIER_PERFORMANCE_DISABLE);
>
> - return 0;
> + return skl_tune_iz_hashing(ring);
> }
>
> int init_workarounds_ring(struct intel_engine_cs *ring)
> --
> 1.8.3.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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