On Friday, June 9, 2017 6:01:37 AM PDT Chris Wilson wrote:
> If we map the bo upon creation, we can avoid the latency of mmapping it
> when querying, and later use the asynchronous, persistent map of the
> predicate to do a quick query.
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Kenneth Graunke <kenn...@whitecape.org>
> Cc: Matt Turner <matts...@gmail.com>
> ---
> src/mesa/drivers/dri/i965/brw_bufmgr.c | 15 +++++++++++++
> src/mesa/drivers/dri/i965/brw_bufmgr.h | 2 ++
> src/mesa/drivers/dri/i965/brw_context.h | 1 +
> src/mesa/drivers/dri/i965/gen6_queryobj.c | 37
> ++++++++++++++++++++++---------
> 4 files changed, 44 insertions(+), 11 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.c
> b/src/mesa/drivers/dri/i965/brw_bufmgr.c
> index 01590a0b0a..9028b538c6 100644
> --- a/src/mesa/drivers/dri/i965/brw_bufmgr.c
> +++ b/src/mesa/drivers/dri/i965/brw_bufmgr.c
> @@ -775,6 +775,21 @@ brw_bo_map(struct brw_context *brw, struct brw_bo *bo,
> unsigned flags)
> return brw_bo_map_gtt(brw, bo, flags);
> }
>
> +void
> +brw_bo_map_sync(struct brw_context *brw, struct brw_bo *bo, unsigned flags)
> +{
> + unsigned domain;
> +
> + if (bo->tiling_mode != I915_TILING_NONE && !(flags & MAP_RAW))
> + domain = I915_GEM_DOMAIN_GTT;
> + else if (can_map_cpu(bo, flags))
> + domain = I915_GEM_DOMAIN_CPU;
> + else
> + domain = I915_GEM_DOMAIN_GTT;
> +
> + set_domain(brw, __func__, bo, domain, flags & MAP_WRITE ? domain : 0);
> +}
> +
> int
> brw_bo_unmap(struct brw_bo *bo)
> {
> diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.h
> b/src/mesa/drivers/dri/i965/brw_bufmgr.h
> index 3a397be695..214b75bf1a 100644
> --- a/src/mesa/drivers/dri/i965/brw_bufmgr.h
> +++ b/src/mesa/drivers/dri/i965/brw_bufmgr.h
> @@ -196,6 +196,8 @@ void brw_bo_unreference(struct brw_bo *bo);
> */
> MUST_CHECK void *brw_bo_map(struct brw_context *brw, struct brw_bo *bo,
> unsigned flags);
>
> +void brw_bo_map_sync(struct brw_context *brw, struct brw_bo *bo, unsigned
> flags);
> +
> /**
> * Reduces the refcount on the userspace mapping of the buffer
> * object.
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h
> b/src/mesa/drivers/dri/i965/brw_context.h
> index c5acb83ad0..117b1ecdca 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -419,6 +419,7 @@ struct brw_query_object {
>
> /** Last query BO associated with this query. */
> struct brw_bo *bo;
> + uint64_t *results;
>
> /** Last index in bo with query data for this object. */
> int last_index;
> diff --git a/src/mesa/drivers/dri/i965/gen6_queryobj.c
> b/src/mesa/drivers/dri/i965/gen6_queryobj.c
> index f913f986ae..18af608166 100644
> --- a/src/mesa/drivers/dri/i965/gen6_queryobj.c
> +++ b/src/mesa/drivers/dri/i965/gen6_queryobj.c
> @@ -221,7 +221,9 @@ gen6_queryobj_get_results(struct gl_context *ctx,
> if (query->bo == NULL)
> return;
>
> - uint64_t *results = brw_bo_map(brw, query->bo, MAP_READ);
> + brw_bo_map_sync(brw, query->bo, MAP_READ | MAP_COHERENT);
> + uint64_t *results = query->results;
> +
> switch (query->Base.Target) {
> case GL_TIME_ELAPSED:
> /* The query BO contains the starting and ending timestamps.
> @@ -296,7 +298,6 @@ gen6_queryobj_get_results(struct gl_context *ctx,
> default:
> unreachable("Unrecognized query target in brw_queryobj_get_results()");
> }
> - brw_bo_unmap(query->bo);
>
> /* Now that we've processed the data stored in the query's buffer object,
> * we can release it.
> @@ -307,6 +308,23 @@ gen6_queryobj_get_results(struct gl_context *ctx,
> query->Base.Ready = true;
> }
>
> +static int gen6_alloc_query(struct brw_context *brw,
> + struct brw_query_object *query)
> +{
> + /* Since we're starting a new query, we need to throw away old results. */
> + if (query->bo)
> + brw_bo_unreference(query->bo);
> +
> + query->bo = brw_bo_alloc(brw->bufmgr, "query results", 4096, 4096);
> + query->results = brw_bo_map(brw, query->bo,
> + MAP_READ | MAP_COHERENT | MAP_ASYNC);
I don't understand why you're using MAP_ASYNC here. We're allocating a new
BO here, and not using the BO_ALLOC_FOR_RENDER flag, so it will be idle.
(brw_bufmgr.c:297 should ensure we never get a busy BO - if the cached BOs
are busy, it will just allocate us a new one.)
So, MAP_ASYNC shouldn't avoid a stall. It does, however, skip the
SET_DOMAIN call, which means that it may not have the right domain
for our new coherent mapping. Hence, you need to whack it later with
your new brw_bo_map_sync() helper.
I think you can drop MAP_ASYNC, and drop brw_bo_map_sync() entirely,
with no ill-effects. Or am I wrong?
> +
> + /* For ARB_query_buffer_object: The result is not available */
> + set_query_availability(brw, query, false);
> +
> + return 0;
> +}
> +
> /**
> * Driver hook for glBeginQuery().
> *
> @@ -318,14 +336,7 @@ gen6_begin_query(struct gl_context *ctx, struct
> gl_query_object *q)
> {
> struct brw_context *brw = brw_context(ctx);
> struct brw_query_object *query = (struct brw_query_object *)q;
> - const int idx = GEN6_QUERY_RESULTS;
> -
> - /* Since we're starting a new query, we need to throw away old results. */
> - brw_bo_unreference(query->bo);
> - query->bo = brw_bo_alloc(brw->bufmgr, "query results", 4096, 4096);
> -
> - /* For ARB_query_buffer_object: The result is not available */
> - set_query_availability(brw, query, false);
> + const int idx = gen6_alloc_query(brw, query) + GEN6_QUERY_RESULTS;
>
> switch (query->Base.Target) {
> case GL_TIME_ELAPSED:
> @@ -539,8 +550,12 @@ gen6_query_counter(struct gl_context *ctx, struct
> gl_query_object *q)
> {
> struct brw_context *brw = brw_context(ctx);
> struct brw_query_object *query = (struct brw_query_object *)q;
> - brw_query_counter(ctx, q);
> + const int idx = gen6_alloc_query(brw, query) + GEN6_QUERY_RESULTS;
> +
> + brw_write_timestamp(brw, query->bo, idx);
> set_query_availability(brw, query, true);
> +
> + query->flushed = false;
> }
>
> /* Initialize Gen6+-specific query object functions. */
>
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