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.mcgee@xxxxxxxxx>
Reviewed-by: Jeff Mcgee <jeff.mcgee@xxxxxxxxx>
Signed-off-by: Damien Lespiau <damien.lespiau@xxxxxxxxx>
---
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
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