Mesa (master): anv/gen9: Optimize slice and subslice load balancing behavior.
GitLab Mirror
gitlab-mirror at kemper.freedesktop.org
Mon Aug 12 21:44:44 UTC 2019
Module: Mesa
Branch: master
Commit: c2fe7a0fb818578d87f12300523d796205edffd5
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=c2fe7a0fb818578d87f12300523d796205edffd5
Author: Francisco Jerez <currojerez at riseup.net>
Date: Wed Jul 17 18:41:38 2019 -0700
anv/gen9: Optimize slice and subslice load balancing behavior.
See "i965/gen9: Optimize slice and subslice load balancing behavior."
for the rationale. According to Jason, improves Aztec Ruins
performance by 2.7%.
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org> (v1)
v2: Undo CPU performance micro-optimization done in i965 and iris due
to lack of data justifying it on anv. Use
cmd_buffer_apply_pipe_flushes wrapper instead of emitting pipe
control command directly. (Jason)
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
---
src/intel/vulkan/anv_genX.h | 4 ++
src/intel/vulkan/anv_private.h | 6 +++
src/intel/vulkan/genX_blorp_exec.c | 4 ++
src/intel/vulkan/genX_cmd_buffer.c | 95 ++++++++++++++++++++++++++++++++++++++
4 files changed, 109 insertions(+)
diff --git a/src/intel/vulkan/anv_genX.h b/src/intel/vulkan/anv_genX.h
index a5435e566a3..06c6b467acf 100644
--- a/src/intel/vulkan/anv_genX.h
+++ b/src/intel/vulkan/anv_genX.h
@@ -44,6 +44,10 @@ void genX(cmd_buffer_apply_pipe_flushes)(struct anv_cmd_buffer *cmd_buffer);
void genX(cmd_buffer_emit_gen7_depth_flush)(struct anv_cmd_buffer *cmd_buffer);
+void genX(cmd_buffer_emit_hashing_mode)(struct anv_cmd_buffer *cmd_buffer,
+ unsigned width, unsigned height,
+ unsigned scale);
+
void genX(flush_pipeline_select_3d)(struct anv_cmd_buffer *cmd_buffer);
void genX(flush_pipeline_select_gpgpu)(struct anv_cmd_buffer *cmd_buffer);
diff --git a/src/intel/vulkan/anv_private.h b/src/intel/vulkan/anv_private.h
index 2465f264354..b381386a716 100644
--- a/src/intel/vulkan/anv_private.h
+++ b/src/intel/vulkan/anv_private.h
@@ -2422,6 +2422,12 @@ struct anv_cmd_state {
bool conditional_render_enabled;
/**
+ * Last rendering scale argument provided to
+ * genX(cmd_buffer_emit_hashing_mode)().
+ */
+ unsigned current_hash_scale;
+
+ /**
* Array length is anv_cmd_state::pass::attachment_count. Array content is
* valid only when recording a render pass instance.
*/
diff --git a/src/intel/vulkan/genX_blorp_exec.c b/src/intel/vulkan/genX_blorp_exec.c
index 1592e7f7e3d..239bfb47433 100644
--- a/src/intel/vulkan/genX_blorp_exec.c
+++ b/src/intel/vulkan/genX_blorp_exec.c
@@ -223,6 +223,10 @@ genX(blorp_exec)(struct blorp_batch *batch,
genX(cmd_buffer_config_l3)(cmd_buffer, cfg);
}
+ const unsigned scale = params->fast_clear_op ? UINT_MAX : 1;
+ genX(cmd_buffer_emit_hashing_mode)(cmd_buffer, params->x1 - params->x0,
+ params->y1 - params->y0, scale);
+
#if GEN_GEN >= 11
/* The PIPE_CONTROL command description says:
*
diff --git a/src/intel/vulkan/genX_cmd_buffer.c b/src/intel/vulkan/genX_cmd_buffer.c
index 86ef1663ac4..10da132115c 100644
--- a/src/intel/vulkan/genX_cmd_buffer.c
+++ b/src/intel/vulkan/genX_cmd_buffer.c
@@ -1595,6 +1595,7 @@ genX(CmdExecuteCommands)(
*/
primary->state.current_pipeline = UINT32_MAX;
primary->state.current_l3_config = NULL;
+ primary->state.current_hash_scale = 0;
/* Each of the secondary command buffers will use its own state base
* address. We need to re-emit state base address for the primary after
@@ -2663,6 +2664,8 @@ genX(cmd_buffer_flush_state)(struct anv_cmd_buffer *cmd_buffer)
genX(cmd_buffer_config_l3)(cmd_buffer, pipeline->urb.l3_config);
+ genX(cmd_buffer_emit_hashing_mode)(cmd_buffer, UINT_MAX, UINT_MAX, 1);
+
genX(flush_pipeline_select_3d)(cmd_buffer);
if (vb_emit) {
@@ -3925,6 +3928,98 @@ genX(cmd_buffer_emit_gen7_depth_flush)(struct anv_cmd_buffer *cmd_buffer)
}
}
+/**
+ * Update the pixel hashing modes that determine the balancing of PS threads
+ * across subslices and slices.
+ *
+ * \param width Width bound of the rendering area (already scaled down if \p
+ * scale is greater than 1).
+ * \param height Height bound of the rendering area (already scaled down if \p
+ * scale is greater than 1).
+ * \param scale The number of framebuffer samples that could potentially be
+ * affected by an individual channel of the PS thread. This is
+ * typically one for single-sampled rendering, but for operations
+ * like CCS resolves and fast clears a single PS invocation may
+ * update a huge number of pixels, in which case a finer
+ * balancing is desirable in order to maximally utilize the
+ * bandwidth available. UINT_MAX can be used as shorthand for
+ * "finest hashing mode available".
+ */
+void
+genX(cmd_buffer_emit_hashing_mode)(struct anv_cmd_buffer *cmd_buffer,
+ unsigned width, unsigned height,
+ unsigned scale)
+{
+#if GEN_GEN == 9
+ const struct gen_device_info *devinfo = &cmd_buffer->device->info;
+ const unsigned slice_hashing[] = {
+ /* Because all Gen9 platforms with more than one slice require
+ * three-way subslice hashing, a single "normal" 16x16 slice hashing
+ * block is guaranteed to suffer from substantial imbalance, with one
+ * subslice receiving twice as much work as the other two in the
+ * slice.
+ *
+ * The performance impact of that would be particularly severe when
+ * three-way hashing is also in use for slice balancing (which is the
+ * case for all Gen9 GT4 platforms), because one of the slices
+ * receives one every three 16x16 blocks in either direction, which
+ * is roughly the periodicity of the underlying subslice imbalance
+ * pattern ("roughly" because in reality the hardware's
+ * implementation of three-way hashing doesn't do exact modulo 3
+ * arithmetic, which somewhat decreases the magnitude of this effect
+ * in practice). This leads to a systematic subslice imbalance
+ * within that slice regardless of the size of the primitive. The
+ * 32x32 hashing mode guarantees that the subslice imbalance within a
+ * single slice hashing block is minimal, largely eliminating this
+ * effect.
+ */
+ _32x32,
+ /* Finest slice hashing mode available. */
+ NORMAL
+ };
+ const unsigned subslice_hashing[] = {
+ /* 16x16 would provide a slight cache locality benefit especially
+ * visible in the sampler L1 cache efficiency of low-bandwidth
+ * non-LLC platforms, but it comes at the cost of greater subslice
+ * imbalance for primitives of dimensions approximately intermediate
+ * between 16x4 and 16x16.
+ */
+ _16x4,
+ /* Finest subslice hashing mode available. */
+ _8x4
+ };
+ /* Dimensions of the smallest hashing block of a given hashing mode. If
+ * the rendering area is smaller than this there can't possibly be any
+ * benefit from switching to this mode, so we optimize out the
+ * transition.
+ */
+ const unsigned min_size[][2] = {
+ { 16, 4 },
+ { 8, 4 }
+ };
+ const unsigned idx = scale > 1;
+
+ if (cmd_buffer->state.current_hash_scale != scale &&
+ (width > min_size[idx][0] || height > min_size[idx][1])) {
+ uint32_t gt_mode;
+
+ anv_pack_struct(>_mode, GENX(GT_MODE),
+ .SliceHashing = (devinfo->num_slices > 1 ? slice_hashing[idx] : 0),
+ .SliceHashingMask = (devinfo->num_slices > 1 ? -1 : 0),
+ .SubsliceHashing = subslice_hashing[idx],
+ .SubsliceHashingMask = -1);
+
+ cmd_buffer->state.pending_pipe_bits |=
+ ANV_PIPE_CS_STALL_BIT | ANV_PIPE_STALL_AT_SCOREBOARD_BIT;
+ genX(cmd_buffer_apply_pipe_flushes)(cmd_buffer);
+
+ emit_lri(&cmd_buffer->batch, GENX(GT_MODE_num), gt_mode);
+
+ cmd_buffer->state.current_hash_scale = scale;
+ }
+#endif
+}
+
static void
cmd_buffer_emit_depth_stencil(struct anv_cmd_buffer *cmd_buffer)
{
More information about the mesa-commit
mailing list