[Mesa-dev] [PATCH 4/9] i965: Map the query results for the life of the bo

[Chris Wilson]

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.

v2: Inline the wait on results; it disappears shortly in the next few
patches.

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>
---
 src/mesa/drivers/dri/i965/brw_context.h   |  1 +
 src/mesa/drivers/dri/i965/gen6_queryobj.c | 40 ++++++++++++++++-------
 2 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 3014fa68aff..840332294e6 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -459,6 +459,7 @@ 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 ffdee4040fc..17c10b135d1 100644
--- a/src/mesa/drivers/dri/i965/gen6_queryobj.c
+++ b/src/mesa/drivers/dri/i965/gen6_queryobj.c
@@ -229,7 +229,9 @@ 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_wait_rendering(query->bo);
+   uint64_t *results = query->results;
+
    switch (query->Base.Target) {
    case GL_TIME_ELAPSED:
       /* The query BO contains the starting and ending timestamps.
@@ -304,7 +306,6 @@ 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.
@@ -315,6 +316,25 @@ 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. */
+   brw_bo_unreference(query->bo);
+
+   query->bo = brw_bo_alloc(brw->bufmgr,
+                            "query results", 4096,
+                            BRW_MEMZONE_OTHER);
+   query->results = brw_bo_map(brw, query->bo,
+                               MAP_COHERENT | MAP_PERSISTENT |
+                               MAP_READ | MAP_ASYNC);
+
+   /* For ARB_query_buffer_object: The result is not available */
+   set_query_availability(brw, query, false);
+
+   return 0;
+}
+
 /**
  * Driver hook for glBeginQuery().
  *
@@ -326,15 +346,7 @@ 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, BRW_MEMZONE_OTHER);
-
-   /* 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:
@@ -548,8 +560,12 @@ 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. */
-- 
2.19.0