[Mesa-dev] [PATCH 04/10] i965: Track last location of bo used for the batch
Chris Wilson
chris at chris-wilson.co.uk
Fri Jul 21 15:36:46 UTC 2017
Borrow a trick from anv, and use the last known index for the bo to skip
a search of the batch->exec_bo when adding a new relocation. In defence
against the bo being used in multiple batches simultaneously, we check
that this slot exists and points back to us.
v2: Also update brw_batch_references()
v3: Reset bo->index on creation (Daniel)
v4: Improved explanation of bo->index (Kenneth)
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Kenneth Graunke <kenneth at whitecape.org>
Cc: Matt Turner <mattst88 at gmail.com>
Cc: Jason Ekstrand <jason.ekstrand at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
src/mesa/drivers/dri/i965/brw_bufmgr.c | 1 +
src/mesa/drivers/dri/i965/brw_bufmgr.h | 10 ++++++++++
src/mesa/drivers/dri/i965/intel_batchbuffer.c | 18 ++++++++++++++++--
3 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.c b/src/mesa/drivers/dri/i965/brw_bufmgr.c
index 46da53d353..9723124e8d 100644
--- a/src/mesa/drivers/dri/i965/brw_bufmgr.c
+++ b/src/mesa/drivers/dri/i965/brw_bufmgr.c
@@ -388,6 +388,7 @@ retry:
p_atomic_set(&bo->refcount, 1);
bo->reusable = true;
bo->cache_coherent = bufmgr->has_llc;
+ bo->index = -1;
pthread_mutex_unlock(&bufmgr->lock);
diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.h b/src/mesa/drivers/dri/i965/brw_bufmgr.h
index 6a6051bb71..083009b52e 100644
--- a/src/mesa/drivers/dri/i965/brw_bufmgr.h
+++ b/src/mesa/drivers/dri/i965/brw_bufmgr.h
@@ -76,6 +76,16 @@ struct brw_bo {
uint64_t offset64;
/**
+ * The validation list index for this buffer, or -1 when not in a batch.
+ * Note that a single buffer may be in multiple batches (contexts), and
+ * this is a global field, which refers to the last batch using the BO.
+ * It should not be considered authoritative, but can be used to avoid a
+ * linear walk of the validation list in the common case by guessing that
+ * exec_bos[bo->index] == bo and confirming whether that's the case.
+ */
+ unsigned int index;
+
+ /**
* Boolean of whether the GPU is definitely not accessing the buffer.
*
* This is only valid when reusable, since non-reusable
diff --git a/src/mesa/drivers/dri/i965/intel_batchbuffer.c b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
index 9364dab7f2..637656dec8 100644
--- a/src/mesa/drivers/dri/i965/intel_batchbuffer.c
+++ b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
@@ -509,12 +509,20 @@ throttle(struct brw_context *brw)
}
}
+#define READ_ONCE(x) (*(volatile __typeof__(x) *)&(x))
+
static void
add_exec_bo(struct intel_batchbuffer *batch, struct brw_bo *bo)
{
if (bo != batch->bo) {
- for (int i = 0; i < batch->exec_count; i++) {
- if (batch->exec_bos[i] == bo)
+ unsigned int index = READ_ONCE(bo->index);
+
+ if (index < batch->exec_count && batch->exec_bos[index] == bo)
+ return;
+
+ /* May have been shared between multiple active batches */
+ for (index = 0; index < batch->exec_count; index++) {
+ if (batch->exec_bos[index] == bo)
return;
}
@@ -547,6 +555,7 @@ add_exec_bo(struct intel_batchbuffer *batch, struct brw_bo *bo)
validation_entry->rsvd1 = 0;
validation_entry->rsvd2 = 0;
+ bo->index = batch->exec_count;
batch->exec_bos[batch->exec_count] = bo;
batch->exec_count++;
batch->aperture_space += bo->size;
@@ -616,6 +625,7 @@ do_flush_locked(struct brw_context *brw, int in_fence_fd, int *out_fence_fd)
struct brw_bo *bo = batch->exec_bos[i];
bo->idle = false;
+ bo->index = -1;
/* Update brw_bo::offset64 */
if (batch->validation_list[i].offset != bo->offset64) {
@@ -722,6 +732,10 @@ brw_batch_has_aperture_space(struct brw_context *brw, unsigned extra_space)
bool
brw_batch_references(struct intel_batchbuffer *batch, struct brw_bo *bo)
{
+ unsigned int index = READ_ONCE(bo->index);
+ if (index < batch->exec_count && batch->exec_bos[index] == bo)
+ return true;
+
for (int i = 0; i < batch->exec_count; i++) {
if (batch->exec_bos[i] == bo)
return true;
--
2.13.3
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