drivers/freedreno/freedreno_batch_cache.c

/*
 * Copyright (C) 2016 Rob Clark <robclark@freedesktop.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Authors:
 *    Rob Clark <robclark@freedesktop.org>
 */

#include "util/hash_table.h"
#include "util/set.h"
#include "util/list.h"
#include "util/u_string.h"
#define XXH_INLINE_ALL
#include "util/xxhash.h"

#include "freedreno_batch.h"
#include "freedreno_batch_cache.h"
#include "freedreno_context.h"
#include "freedreno_resource.h"

/* Overview:
 *
 *   The batch cache provides lookup for mapping pipe_framebuffer_state
 *   to a batch.
 *
 *   It does this via hashtable, with key that roughly matches the
 *   pipe_framebuffer_state, as described below.
 *
 * Batch Cache hashtable key:
 *
 *   To serialize the key, and to avoid dealing with holding a reference to
 *   pipe_surface's (which hold a reference to pipe_resource and complicate
 *   the whole refcnting thing), the key is variable length and inline's the
 *   pertinent details of the pipe_surface.
 *
 * Batch:
 *
 *   Each batch needs to hold a reference to each resource it depends on (ie.
 *   anything that needs a mem2gmem).  And a weak reference to resources it
 *   renders to.  (If both src[n] and dst[n] are not NULL then they are the
 *   same.)
 *
 *   When a resource is destroyed, we need to remove entries in the batch
 *   cache that reference the resource, to avoid dangling pointer issues.
 *   So each resource holds a hashset of batches which have reference them
 *   in their hashtable key.
 *
 *   When a batch has weak reference to no more resources (ie. all the
 *   surfaces it rendered to are destroyed) the batch can be destroyed.
 *   Could happen in an app that renders and never uses the result.  More
 *   common scenario, I think, will be that some, but not all, of the
 *   surfaces are destroyed before the batch is submitted.
 *
 *   If (for example), batch writes to zsbuf but that surface is destroyed
 *   before batch is submitted, we can skip gmem2mem (but still need to
 *   alloc gmem space as before.  If the batch depended on previous contents
 *   of that surface, it would be holding a reference so the surface would
 *   not have been destroyed.
 */

struct key {
	uint32_t width, height, layers;
	uint16_t samples, num_surfs;
	struct fd_context *ctx;
	struct {
		struct pipe_resource *texture;
		union pipe_surface_desc u;
		uint8_t pos, samples;
		uint16_t format;
	} surf[0];
};

static struct key *
key_alloc(unsigned num_surfs)
{
	struct key *key =
		CALLOC_VARIANT_LENGTH_STRUCT(key, sizeof(key->surf[0]) * num_surfs);
	return key;
}

static uint32_t
key_hash(const void *_key)
{
	const struct key *key = _key;
	uint32_t hash = 0;
	hash = XXH32(key, offsetof(struct key, surf[0]), hash);
	hash = XXH32(key->surf, sizeof(key->surf[0]) * key->num_surfs , hash);
	return hash;
}

static bool
key_equals(const void *_a, const void *_b)
{
	const struct key *a = _a;
	const struct key *b = _b;
	return (memcmp(a, b, offsetof(struct key, surf[0])) == 0) &&
		(memcmp(a->surf, b->surf, sizeof(a->surf[0]) * a->num_surfs) == 0);
}

void
fd_bc_init(struct fd_batch_cache *cache)
{
	cache->ht = _mesa_hash_table_create(NULL, key_hash, key_equals);
}

void
fd_bc_fini(struct fd_batch_cache *cache)
{
	_mesa_hash_table_destroy(cache->ht, NULL);
}

static void
bc_flush(struct fd_batch_cache *cache, struct fd_context *ctx, bool deferred)
{
	/* fd_batch_flush() (and fd_batch_add_dep() which calls it indirectly)
	 * can cause batches to be unref'd and freed under our feet, so grab
	 * a reference to all the batches we need up-front.
	 */
	struct fd_batch *batches[ARRAY_SIZE(cache->batches)] = {0};
	struct fd_batch *batch;
	unsigned n = 0;

	fd_context_lock(ctx);

	foreach_batch(batch, cache, cache->batch_mask) {
		if (batch->ctx == ctx) {
			fd_batch_reference_locked(&batches[n++], batch);
		}
	}

	if (deferred) {
		struct fd_batch *current_batch = fd_context_batch(ctx);

		for (unsigned i = 0; i < n; i++) {
			if (batches[i] && (batches[i]->ctx == ctx) &&
					(batches[i] != current_batch)) {
				fd_batch_add_dep(current_batch, batches[i]);
			}
		}

		fd_context_unlock(ctx);
	} else {
		fd_context_unlock(ctx);

		for (unsigned i = 0; i < n; i++) {
			fd_batch_flush(batches[i]);
		}
	}

	for (unsigned i = 0; i < n; i++) {
		fd_batch_reference(&batches[i], NULL);
	}
}

void
fd_bc_flush(struct fd_batch_cache *cache, struct fd_context *ctx)
{
	bc_flush(cache, ctx, false);
}

/* deferred flush doesn't actually flush, but it marks every other
 * batch associated with the context as dependent on the current
 * batch.  So when the current batch gets flushed, all other batches
 * that came before also get flushed.
 */
void
fd_bc_flush_deferred(struct fd_batch_cache *cache, struct fd_context *ctx)
{
	bc_flush(cache, ctx, true);
}

static bool
batch_in_cache(struct fd_batch_cache *cache, struct fd_batch *batch)
{
	struct fd_batch *b;

	foreach_batch (b, cache, cache->batch_mask)
		if (b == batch)
			return true;

	return false;
}

void
fd_bc_dump(struct fd_screen *screen, const char *fmt, ...)
{
	struct fd_batch_cache *cache = &screen->batch_cache;

	if (!BATCH_DEBUG)
		return;

	fd_screen_lock(screen);

	va_list ap;
	va_start(ap, fmt);
	vprintf(fmt, ap);
	va_end(ap);

	set_foreach (screen->live_batches, entry) {
		struct fd_batch *batch = (struct fd_batch *)entry->key;
		printf("  %p<%u>%s%s\n", batch, batch->seqno,
				batch->needs_flush ? ", NEEDS FLUSH" : "",
				batch_in_cache(cache, batch) ? "" : ", ORPHAN");
	}

	printf("----\n");

	fd_screen_unlock(screen);
}

void
fd_bc_invalidate_context(struct fd_context *ctx)
{
	struct fd_batch_cache *cache = &ctx->screen->batch_cache;
	struct fd_batch *batch;

	fd_screen_lock(ctx->screen);

	foreach_batch(batch, cache, cache->batch_mask) {
		if (batch->ctx == ctx)
			fd_bc_invalidate_batch(batch, true);
	}

	fd_screen_unlock(ctx->screen);
}

/**
 * Note that when batch is flushed, it needs to remain in the cache so
 * that fd_bc_invalidate_resource() can work.. otherwise we can have
 * the case where a rsc is destroyed while a batch still has a dangling
 * reference to it.
 *
 * Note that the cmdstream (or, after the SUBMIT ioctl, the kernel)
 * would have a reference to the underlying bo, so it is ok for the
 * rsc to be destroyed before the batch.
 */
void
fd_bc_invalidate_batch(struct fd_batch *batch, bool remove)
{
	if (!batch)
		return;

	struct fd_batch_cache *cache = &batch->ctx->screen->batch_cache;
	struct key *key = (struct key *)batch->key;

	fd_context_assert_locked(batch->ctx);

	if (remove) {
		cache->batches[batch->idx] = NULL;
		cache->batch_mask &= ~(1 << batch->idx);
	}

	if (!key)
		return;

	DBG("%p: key=%p", batch, batch->key);
	for (unsigned idx = 0; idx < key->num_surfs; idx++) {
		struct fd_resource *rsc = fd_resource(key->surf[idx].texture);
		rsc->bc_batch_mask &= ~(1 << batch->idx);
	}

	struct hash_entry *entry =
		_mesa_hash_table_search_pre_hashed(cache->ht, batch->hash, key);
	_mesa_hash_table_remove(cache->ht, entry);

	batch->key = NULL;
	free(key);
}

void
fd_bc_invalidate_resource(struct fd_resource *rsc, bool destroy)
{
	struct fd_screen *screen = fd_screen(rsc->base.screen);
	struct fd_batch *batch;

	fd_screen_lock(screen);

	if (destroy) {
		foreach_batch(batch, &screen->batch_cache, rsc->batch_mask) {
			struct set_entry *entry = _mesa_set_search(batch->resources, rsc);
			_mesa_set_remove(batch->resources, entry);
		}
		rsc->batch_mask = 0;

		fd_batch_reference_locked(&rsc->write_batch, NULL);
	}

	foreach_batch(batch, &screen->batch_cache, rsc->bc_batch_mask)
		fd_bc_invalidate_batch(batch, false);

	rsc->bc_batch_mask = 0;

	fd_screen_unlock(screen);
}

struct fd_batch *
fd_bc_alloc_batch(struct fd_batch_cache *cache, struct fd_context *ctx, bool nondraw)
{
	struct fd_batch *batch;
	uint32_t idx;

	fd_screen_lock(ctx->screen);

	while ((idx = ffs(~cache->batch_mask)) == 0) {
#if 0
		for (unsigned i = 0; i < ARRAY_SIZE(cache->batches); i++) {
			batch = cache->batches[i];
			debug_printf("%d: needs_flush=%d, depends:", batch->idx, batch->needs_flush);
			set_foreach(batch->dependencies, entry) {
				struct fd_batch *dep = (struct fd_batch *)entry->key;
				debug_printf(" %d", dep->idx);
			}
			debug_printf("\n");
		}
#endif
		/* TODO: is LRU the better policy?  Or perhaps the batch that
		 * depends on the fewest other batches?
		 */
		struct fd_batch *flush_batch = NULL;
		for (unsigned i = 0; i < ARRAY_SIZE(cache->batches); i++) {
			if (!flush_batch || (cache->batches[i]->seqno < flush_batch->seqno))
				fd_batch_reference_locked(&flush_batch, cache->batches[i]);
		}

		/* we can drop lock temporarily here, since we hold a ref,
		 * flush_batch won't disappear under us.
		 */
		fd_screen_unlock(ctx->screen);
		DBG("%p: too many batches!  flush forced!", flush_batch);
		fd_batch_flush(flush_batch);
		fd_screen_lock(ctx->screen);

		/* While the resources get cleaned up automatically, the flush_batch
		 * doesn't get removed from the dependencies of other batches, so
		 * it won't be unref'd and will remain in the table.
		 *
		 * TODO maybe keep a bitmask of batches that depend on me, to make
		 * this easier:
		 */
		for (unsigned i = 0; i < ARRAY_SIZE(cache->batches); i++) {
			struct fd_batch *other = cache->batches[i];
			if (!other)
				continue;
			if (other->dependents_mask & (1 << flush_batch->idx)) {
				other->dependents_mask &= ~(1 << flush_batch->idx);
				struct fd_batch *ref = flush_batch;
				fd_batch_reference_locked(&ref, NULL);
			}
		}

		fd_batch_reference_locked(&flush_batch, NULL);
	}

	idx--;              /* bit zero returns 1 for ffs() */

	batch = fd_batch_create(ctx, nondraw);
	if (!batch)
		goto out;

	batch->seqno = cache->cnt++;
	batch->idx = idx;
	cache->batch_mask |= (1 << idx);

	debug_assert(cache->batches[idx] == NULL);
	cache->batches[idx] = batch;

out:
	fd_screen_unlock(ctx->screen);

	return batch;
}

static struct fd_batch *
batch_from_key(struct fd_batch_cache *cache, struct key *key,
		struct fd_context *ctx)
{
	struct fd_batch *batch = NULL;
	uint32_t hash = key_hash(key);
	struct hash_entry *entry =
		_mesa_hash_table_search_pre_hashed(cache->ht, hash, key);

	if (entry) {
		free(key);
		fd_batch_reference(&batch, (struct fd_batch *)entry->data);
		return batch;
	}

	batch = fd_bc_alloc_batch(cache, ctx, false);
#ifdef DEBUG
	DBG("%p: hash=0x%08x, %ux%u, %u layers, %u samples", batch, hash,
			key->width, key->height, key->layers, key->samples);
	for (unsigned idx = 0; idx < key->num_surfs; idx++) {
		DBG("%p:  surf[%u]: %p (%s) (%u,%u / %u,%u,%u)", batch, key->surf[idx].pos,
			key->surf[idx].texture, util_format_name(key->surf[idx].format),
			key->surf[idx].u.buf.first_element, key->surf[idx].u.buf.last_element,
			key->surf[idx].u.tex.first_layer, key->surf[idx].u.tex.last_layer,
			key->surf[idx].u.tex.level);
	}
#endif
	if (!batch)
		return NULL;

	/* reset max_scissor, which will be adjusted on draws
	 * according to the actual scissor.
	 */
	batch->max_scissor.minx = ~0;
	batch->max_scissor.miny = ~0;
	batch->max_scissor.maxx = 0;
	batch->max_scissor.maxy = 0;

	fd_screen_lock(ctx->screen);

	_mesa_hash_table_insert_pre_hashed(cache->ht, hash, key, batch);
	batch->key = key;
	batch->hash = hash;

	for (unsigned idx = 0; idx < key->num_surfs; idx++) {
		struct fd_resource *rsc = fd_resource(key->surf[idx].texture);
		rsc->bc_batch_mask = (1 << batch->idx);
	}

	fd_screen_unlock(ctx->screen);

	return batch;
}

static void
key_surf(struct key *key, unsigned idx, unsigned pos, struct pipe_surface *psurf)
{
	key->surf[idx].texture = psurf->texture;
	key->surf[idx].u = psurf->u;
	key->surf[idx].pos = pos;
	key->surf[idx].samples = MAX2(1, psurf->nr_samples);
	key->surf[idx].format = psurf->format;
}

struct fd_batch *
fd_batch_from_fb(struct fd_batch_cache *cache, struct fd_context *ctx,
		const struct pipe_framebuffer_state *pfb)
{
	unsigned idx = 0, n = pfb->nr_cbufs + (pfb->zsbuf ? 1 : 0);
	struct key *key = key_alloc(n);

	key->width = pfb->width;
	key->height = pfb->height;
	key->layers = pfb->layers;
	key->samples = util_framebuffer_get_num_samples(pfb);
	key->ctx = ctx;

	if (pfb->zsbuf)
		key_surf(key, idx++, 0, pfb->zsbuf);

	for (unsigned i = 0; i < pfb->nr_cbufs; i++)
		if (pfb->cbufs[i])
			key_surf(key, idx++, i + 1, pfb->cbufs[i]);

	key->num_surfs = idx;

	return batch_from_key(cache, key, ctx);
}