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drm/i915/skl: Tune IZ hashing when subslices are unbalanced

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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@intel.com>
Reviewed-by: Jeff Mcgee <jeff.mcgee@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Damien Lespiau 2015-02-14 18:30:29 +00:00 committed by Daniel Vetter
parent cb0a08c1ed
commit b766879106
4 changed files with 62 additions and 4 deletions
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17
drivers/gpu/drm/i915/i915_dma.c
View file

@ -650,13 +650,24 @@ 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;
}
}

2
drivers/gpu/drm/i915/i915_drv.h
View file

@ -700,6 +700,8 @@ 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;

2
drivers/gpu/drm/i915/i915_reg.h
View file

@ -1351,6 +1351,8 @@ 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

45
drivers/gpu/drm/i915/intel_ringbuffer.c
View file

@ -1002,6 +1002,49 @@ 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;
@ -1014,7 +1057,7 @@ static int skl_init_workarounds(struct intel_engine_cs *ring)
WA_SET_BIT_MASKED(HIZ_CHICKEN,
BDW_HIZ_POWER_COMPILER_CLOCK_GATING_DISABLE);
return 0;
return skl_tune_iz_hashing(ring);
}
int init_workarounds_ring(struct intel_engine_cs *ring)