radeonsi: add a slab allocator for bindless descriptors

For each texture/image handles, we need to allocate a new
buffer for the bindless descriptor. But when the number of
buffers added to the current CS becomes high, the overhead
in the winsys (and in the kernel) is important.

To reduce this bottleneck, the idea is to suballocate the
bindless descriptors using a slab similar to the one used
in the winsys.

Currently, a buffer can hold 1024 bindless descriptors but
this limit is arbitrary and could be changed in the future
for some reasons. Once a slab is allocated the "base" buffer
is added to a per-context list.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

diff --git a/src/gallium/drivers/radeonsi/si_descriptors.c b/src/gallium/drivers/radeonsi/si_descriptors.c
index 32d6cbe94c63f43395abcd34ea6452cb63ee5657..7d0a8f9738bd1ad425e2ace0b9468f0ae9495aa6 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_descriptors.c
+++ b/src/gallium/drivers/radeonsi/si_descriptors.c
@@ -2036,6 +2036,90 @@ void si_emit_compute_shader_userdata(struct si_context *sctx)
        sctx->shader_pointers_dirty &= ~compute_mask;
 }
 
+/* BINDLESS */
+
+struct si_bindless_descriptor_slab
+{
+       struct pb_slab base;
+       struct r600_resource *buffer;
+       struct si_bindless_descriptor *entries;
+};
+
+bool si_bindless_descriptor_can_reclaim_slab(void *priv,
+                                            struct pb_slab_entry *entry)
+{
+       /* Do not allow to reclaim any bindless descriptors for now because the
+        * GPU might be using them. This should be improved later on.
+        */
+       return false;
+}
+
+struct pb_slab *si_bindless_descriptor_slab_alloc(void *priv, unsigned heap,
+                                                 unsigned entry_size,
+                                                 unsigned group_index)
+{
+       struct si_context *sctx = priv;
+       struct si_screen *sscreen = sctx->screen;
+       struct si_bindless_descriptor_slab *slab;
+
+       slab = CALLOC_STRUCT(si_bindless_descriptor_slab);
+       if (!slab)
+               return NULL;
+
+       /* Create a buffer in VRAM for 1024 bindless descriptors. */
+       slab->buffer = (struct r600_resource *)
+               pipe_buffer_create(&sscreen->b.b, 0,
+                                  PIPE_USAGE_DEFAULT, 64 * 1024);
+       if (!slab->buffer)
+               goto fail;
+
+       slab->base.num_entries = slab->buffer->bo_size / entry_size;
+       slab->base.num_free = slab->base.num_entries;
+       slab->entries = CALLOC(slab->base.num_entries, sizeof(*slab->entries));
+       if (!slab->entries)
+               goto fail_buffer;
+
+       LIST_INITHEAD(&slab->base.free);
+
+       for (unsigned i = 0; i < slab->base.num_entries; ++i) {
+               struct si_bindless_descriptor *desc = &slab->entries[i];
+
+               desc->entry.slab = &slab->base;
+               desc->entry.group_index = group_index;
+               desc->buffer = slab->buffer;
+               desc->offset = i * entry_size;
+
+               LIST_ADDTAIL(&desc->entry.head, &slab->base.free);
+       }
+
+       /* Add the descriptor to the per-context list. */
+       util_dynarray_append(&sctx->bindless_descriptors,
+                           struct r600_resource *, slab->buffer);
+
+       return &slab->base;
+
+fail_buffer:
+       r600_resource_reference(&slab->buffer, NULL);
+fail:
+       FREE(slab);
+       return NULL;
+}
+
+void si_bindless_descriptor_slab_free(void *priv, struct pb_slab *pslab)
+{
+       struct si_context *sctx = priv;
+       struct si_bindless_descriptor_slab *slab =
+               (struct si_bindless_descriptor_slab *)pslab;
+
+       /* Remove the descriptor from the per-context list. */
+       util_dynarray_delete_unordered(&sctx->bindless_descriptors,
+                                      struct r600_resource *, slab->buffer);
+
+       r600_resource_reference(&slab->buffer, NULL);
+       FREE(slab->entries);
+       FREE(slab);
+}
+
 /* INIT/DEINIT/UPLOAD */
 
 /* GFX9 has only 4KB of CE, while previous chips had 32KB. In order

diff --git a/src/gallium/drivers/radeonsi/si_pipe.c b/src/gallium/drivers/radeonsi/si_pipe.c
index 031e4731bf01d0ff52ad9d3e89f84dc26d38c539..14fe9dd6a36ebe565539ec48a96ea12e486bccdc 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_pipe.c
+++ b/src/gallium/drivers/radeonsi/si_pipe.c
@@ -94,6 +94,9 @@ static void si_destroy_context(struct pipe_context *context)
        r600_resource_reference(&sctx->last_trace_buf, NULL);
        radeon_clear_saved_cs(&sctx->last_gfx);
 
+       pb_slabs_deinit(&sctx->bindless_descriptor_slabs);
+       util_dynarray_fini(&sctx->bindless_descriptors);
+
        FREE(sctx);
 }
 
@@ -316,6 +319,15 @@ static struct pipe_context *si_create_context(struct pipe_screen *screen,
 
        sctx->tm = si_create_llvm_target_machine(sscreen);
 
+       /* Create a slab allocator for all bindless descriptors. */
+       if (!pb_slabs_init(&sctx->bindless_descriptor_slabs, 6, 6, 1, sctx,
+                          si_bindless_descriptor_can_reclaim_slab,
+                          si_bindless_descriptor_slab_alloc,
+                          si_bindless_descriptor_slab_free))
+               goto fail;
+
+       util_dynarray_init(&sctx->bindless_descriptors, NULL);
+
        return &sctx->b.b;
 fail:
        fprintf(stderr, "radeonsi: Failed to create a context.\n");

diff --git a/src/gallium/drivers/radeonsi/si_pipe.h b/src/gallium/drivers/radeonsi/si_pipe.h
index eef05cf33673a848f56801c368aeccdd2516a6d7..0d8128c88dc1a14982415ccc79dcd8211abd8409 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_pipe.h
+++ b/src/gallium/drivers/radeonsi/si_pipe.h
@@ -28,6 +28,8 @@
 
 #include "si_shader.h"
 
+#include "util/u_dynarray.h"
+
 #ifdef PIPE_ARCH_BIG_ENDIAN
 #define SI_BIG_ENDIAN 1
 #else
@@ -228,6 +230,13 @@ union si_vgt_param_key {
        uint32_t index;
 };
 
+struct si_bindless_descriptor
+{
+       struct pb_slab_entry            entry;
+       struct r600_resource            *buffer;
+       unsigned                        offset;
+};
+
 struct si_context {
        struct r600_common_context      b;
        struct blitter_context          *blitter;
@@ -390,6 +399,12 @@ struct si_context {
        /* Precomputed IA_MULTI_VGT_PARAM */
        union si_vgt_param_key  ia_multi_vgt_param_key;
        unsigned                ia_multi_vgt_param[SI_NUM_VGT_PARAM_STATES];
+
+       /* Slab allocator for bindless descriptors. */
+       struct pb_slabs         bindless_descriptor_slabs;
+
+       /* Bindless descriptors. */
+       struct util_dynarray    bindless_descriptors;
 };
 
 /* cik_sdma.c */

diff --git a/src/gallium/drivers/radeonsi/si_state.h b/src/gallium/drivers/radeonsi/si_state.h
index d8bf13e794ad8364e4fe6c733bb7c50582e3df60..55227a156b590d65ec5dbe569167864a2e34a2ca 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_state.h
+++ b/src/gallium/drivers/radeonsi/si_state.h
@@ -30,6 +30,8 @@
 #include "si_pm4.h"
 #include "radeon/r600_pipe_common.h"
 
+#include "pipebuffer/pb_slab.h"
+
 #define SI_NUM_GRAPHICS_SHADERS (PIPE_SHADER_TESS_EVAL+1)
 #define SI_NUM_SHADERS (PIPE_SHADER_COMPUTE+1)
 
@@ -340,6 +342,12 @@ void si_set_active_descriptors(struct si_context *sctx, unsigned desc_idx,
                               uint64_t new_active_mask);
 void si_set_active_descriptors_for_shader(struct si_context *sctx,
                                          struct si_shader_selector *sel);
+bool si_bindless_descriptor_can_reclaim_slab(void *priv,
+                                            struct pb_slab_entry *entry);
+struct pb_slab *si_bindless_descriptor_slab_alloc(void *priv, unsigned heap,
+                                                 unsigned entry_size,
+                                                 unsigned group_index);
+void si_bindless_descriptor_slab_free(void *priv, struct pb_slab *pslab);
 
 /* si_state.c */
 struct si_shader_selector;