diff options
Diffstat (limited to 'src/mesa')
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_queryobj.c | 159 |
1 files changed, 143 insertions, 16 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_queryobj.c b/src/mesa/drivers/dri/i965/brw_queryobj.c index c6ed8e26d32..8def39cf314 100644 --- a/src/mesa/drivers/dri/i965/brw_queryobj.c +++ b/src/mesa/drivers/dri/i965/brw_queryobj.c @@ -34,11 +34,6 @@ * fragments that passed the depth test, or the hardware timer. They are * appropriately synced with the stage of the pipeline for our extensions' * needs. - * - * To avoid getting samples from another context's rendering in our results, - * we capture the counts at the start and end of every batchbuffer while the - * query is active, and sum up the differences. (We should do so for - * GL_TIME_ELAPSED as well, but don't). */ #include "main/imports.h" @@ -48,6 +43,9 @@ #include "intel_batchbuffer.h" #include "intel_reg.h" +/** + * Emit PIPE_CONTROLs to write the current GPU timestamp into a buffer. + */ static void write_timestamp(struct intel_context *intel, drm_intel_bo *query_bo, int idx) { @@ -90,6 +88,9 @@ write_timestamp(struct intel_context *intel, drm_intel_bo *query_bo, int idx) } } +/** + * Emit PIPE_CONTROLs to write the PS_DEPTH_COUNT register into a buffer. + */ static void write_depth_count(struct intel_context *intel, drm_intel_bo *query_bo, int idx) { @@ -129,7 +130,9 @@ write_depth_count(struct intel_context *intel, drm_intel_bo *query_bo, int idx) } } -/** Waits on the query object's BO and totals the results for this query */ +/** + * Wait on the query object's BO and calculate the final result. + */ static void brw_queryobj_get_results(struct gl_context *ctx, struct brw_query_object *query) @@ -142,6 +145,10 @@ brw_queryobj_get_results(struct gl_context *ctx, if (query->bo == NULL) return; + /* If the application has requested the query result, but this batch is + * still contributing to it, flush it now so the results will be present + * when mapped. + */ if (drm_intel_bo_references(intel->batch.bo, query->bo)) intel_batchbuffer_flush(intel); @@ -155,6 +162,9 @@ brw_queryobj_get_results(struct gl_context *ctx, results = query->bo->virtual; switch (query->Base.Target) { case GL_TIME_ELAPSED_EXT: + /* The query BO contains the starting and ending timestamps. + * Subtract the two and convert to nanoseconds. + */ if (intel->gen >= 6) query->Base.Result += 80 * (results[1] - results[0]); else @@ -162,6 +172,7 @@ brw_queryobj_get_results(struct gl_context *ctx, break; case GL_TIMESTAMP: + /* The query BO contains a single timestamp value in results[0]. */ if (intel->gen >= 6) { /* Our timer is a clock that increments every 80ns (regardless of * other clock scaling in the system). The timestamp register we can @@ -187,7 +198,16 @@ brw_queryobj_get_results(struct gl_context *ctx, break; case GL_SAMPLES_PASSED_ARB: - /* Map and count the pixels from the current query BO */ + /* Loop over pairs of values from the BO, which are the PS_DEPTH_COUNT + * value at the start and end of the batchbuffer. Subtract them to + * get the number of fragments which passed the depth test in each + * individual batch, and add those differences up to get the number + * of fragments for the entire query. + * + * Note that query->Base.Result may already be non-zero. We may have + * run out of space in the query's BO and allocated a new one. If so, + * this function was already called to accumulate the results so far. + */ for (i = query->first_index; i <= query->last_index; i++) { query->Base.Result += results[i * 2 + 1] - results[i * 2]; } @@ -195,7 +215,9 @@ brw_queryobj_get_results(struct gl_context *ctx, case GL_ANY_SAMPLES_PASSED: case GL_ANY_SAMPLES_PASSED_CONSERVATIVE: - /* Set true if any of the sub-queries passed. */ + /* If the starting and ending PS_DEPTH_COUNT from any of the batches + * differ, then some fragments passed the depth test. + */ for (i = query->first_index; i <= query->last_index; i++) { if (results[i * 2 + 1] != results[i * 2]) { query->Base.Result = GL_TRUE; @@ -218,10 +240,18 @@ brw_queryobj_get_results(struct gl_context *ctx, } drm_intel_bo_unmap(query->bo); + /* Now that we've processed the data stored in the query's buffer object, + * we can release it. + */ drm_intel_bo_unreference(query->bo); query->bo = NULL; } +/** + * The NewQueryObject() driver hook. + * + * Allocates and initializes a new query object. + */ static struct gl_query_object * brw_new_query_object(struct gl_context *ctx, GLuint id) { @@ -237,6 +267,9 @@ brw_new_query_object(struct gl_context *ctx, GLuint id) return &query->Base; } +/** + * The DeleteQuery() driver hook. + */ static void brw_delete_query(struct gl_context *ctx, struct gl_query_object *q) { @@ -246,6 +279,12 @@ brw_delete_query(struct gl_context *ctx, struct gl_query_object *q) free(query); } +/** + * Driver hook for glBeginQuery(). + * + * Initializes driver structures and emits any GPU commands required to begin + * recording data for the query. + */ static void brw_begin_query(struct gl_context *ctx, struct gl_query_object *q) { @@ -255,6 +294,25 @@ brw_begin_query(struct gl_context *ctx, struct gl_query_object *q) switch (query->Base.Target) { case GL_TIME_ELAPSED_EXT: + /* For timestamp queries, we record the starting time right away so that + * we measure the full time between BeginQuery and EndQuery. There's + * some debate about whether this is the right thing to do. Our decision + * is based on the following text from the ARB_timer_query extension: + * + * "(5) Should the extension measure total time elapsed between the full + * completion of the BeginQuery and EndQuery commands, or just time + * spent in the graphics library? + * + * RESOLVED: This extension will measure the total time elapsed + * between the full completion of these commands. Future extensions + * may implement a query to determine time elapsed at different stages + * of the graphics pipeline." + * + * We write a starting timestamp now (at index 0). At EndQuery() time, + * we'll write a second timestamp (at index 1), and subtract the two to + * obtain the time elapsed. Notably, this includes time elapsed while + * the system was doing other work, such as running other applications. + */ drm_intel_bo_unreference(query->bo); query->bo = drm_intel_bo_alloc(intel->bufmgr, "timer query", 4096, 4096); write_timestamp(intel, query->bo, 0); @@ -263,13 +321,24 @@ brw_begin_query(struct gl_context *ctx, struct gl_query_object *q) case GL_ANY_SAMPLES_PASSED: case GL_ANY_SAMPLES_PASSED_CONSERVATIVE: case GL_SAMPLES_PASSED_ARB: - /* Reset our driver's tracking of query state. */ + /* For occlusion queries, we delay taking an initial sample until the + * first drawing occurs in this batch. See the reasoning in the comments + * for brw_emit_query_begin() below. + * + * Since we're starting a new query, we need to be sure to throw away + * any previous occlusion query results. + */ drm_intel_bo_unreference(query->bo); query->bo = NULL; query->first_index = -1; query->last_index = -1; brw->query.obj = query; + + /* Depth statistics on Gen4 require strange workarounds, so we try to + * avoid them when necessary. They're required for occlusion queries, + * so turn them on now. + */ intel->stats_wm++; break; @@ -296,7 +365,12 @@ brw_begin_query(struct gl_context *ctx, struct gl_query_object *q) } /** - * Begin the ARB_occlusion_query query on a query object. + * Driver hook for glEndQuery(). + * + * Emits GPU commands to record a final query value, ending any data capturing. + * However, the final result isn't necessarily available until the GPU processes + * those commands. brw_queryobj_get_results() processes the captured data to + * produce the final result. */ static void brw_end_query(struct gl_context *ctx, struct gl_query_object *q) @@ -307,6 +381,7 @@ brw_end_query(struct gl_context *ctx, struct gl_query_object *q) switch (query->Base.Target) { case GL_TIME_ELAPSED_EXT: + /* Write the final timestamp. */ write_timestamp(intel, query->bo, 1); break; @@ -376,6 +451,12 @@ brw_end_query(struct gl_context *ctx, struct gl_query_object *q) } } +/** + * The WaitQuery() driver hook. + * + * Wait for a query result to become available and return it. This is the + * backing for glGetQueryObjectiv() with the GL_QUERY_RESULT pname. + */ static void brw_wait_query(struct gl_context *ctx, struct gl_query_object *q) { struct brw_query_object *query = (struct brw_query_object *)q; @@ -384,6 +465,12 @@ static void brw_wait_query(struct gl_context *ctx, struct gl_query_object *q) query->Base.Ready = true; } +/** + * The CheckQuery() driver hook. + * + * Checks whether a query result is ready yet. If not, flushes. + * This is the backing for glGetQueryObjectiv()'s QUERY_RESULT_AVAILABLE pname. + */ static void brw_check_query(struct gl_context *ctx, struct gl_query_object *q) { struct intel_context *intel = intel_context(ctx); @@ -405,7 +492,28 @@ static void brw_check_query(struct gl_context *ctx, struct gl_query_object *q) } } -/** Called just before primitive drawing to get a beginning PS_DEPTH_COUNT. */ +/** + * Record the PS_DEPTH_COUNT value (for occlusion queries) just before + * primitive drawing. + * + * In a pre-hardware context world, the single PS_DEPTH_COUNT register is + * shared among all applications using the GPU. However, our query value + * needs to only include fragments generated by our application/GL context. + * + * To accommodate this, we record PS_DEPTH_COUNT at the start and end of + * each batchbuffer (technically, the first primitive drawn and flush time). + * Subtracting each pair of values calculates the change in PS_DEPTH_COUNT + * caused by a batchbuffer. Since there is no preemption inside batches, + * this is guaranteed to only measure the effects of our current application. + * + * Adding each of these differences (in case drawing is done over many batches) + * produces the final expected value. + * + * In a world with hardware contexts, PS_DEPTH_COUNT is saved and restored + * as part of the context state, so this is unnecessary. We could simply + * read two values and subtract them. However, it's safe to continue using + * the old approach. + */ void brw_emit_query_begin(struct brw_context *brw) { @@ -413,11 +521,16 @@ brw_emit_query_begin(struct brw_context *brw) struct gl_context *ctx = &intel->ctx; struct brw_query_object *query = brw->query.obj; - /* Skip if we're not doing any queries, or we've emitted the start. */ + /* Skip if we're not doing any queries, or we've already recorded the + * initial query value for this batchbuffer. + */ if (!query || brw->query.begin_emitted) return; - /* Get a new query BO if we're going to need it. */ + /* Ensure the buffer has enough space to store a new pair of values. + * If not, create a new one of the same size; we'll gather the existing + * buffer's results momentarily. + */ if (brw->query.bo == NULL || brw->query.index * 2 + 1 >= 4096 / sizeof(uint64_t)) { drm_intel_bo_unreference(brw->query.bo); @@ -425,7 +538,7 @@ brw_emit_query_begin(struct brw_context *brw) brw->query.bo = drm_intel_bo_alloc(intel->bufmgr, "query", 4096, 1); - /* clear target buffer */ + /* Fill the buffer with zeroes. This is probably superfluous. */ drm_intel_bo_map(brw->query.bo, true); memset((char *)brw->query.bo->virtual, 0, 4096); drm_intel_bo_unmap(brw->query.bo); @@ -436,8 +549,13 @@ brw_emit_query_begin(struct brw_context *brw) write_depth_count(intel, brw->query.bo, brw->query.index * 2); if (query->bo != brw->query.bo) { - if (query->bo != NULL) + if (query->bo != NULL) { + /* The old query BO did not have enough space, so we allocated a new + * one. Gather the results so far (adding up the differences) and + * release the old BO. + */ brw_queryobj_get_results(ctx, query); + } drm_intel_bo_reference(brw->query.bo); query->bo = brw->query.bo; query->first_index = brw->query.index; @@ -446,7 +564,11 @@ brw_emit_query_begin(struct brw_context *brw) brw->query.begin_emitted = true; } -/** Called at batchbuffer flush to get an ending PS_DEPTH_COUNT */ +/** + * Called at batchbuffer flush to get an ending PS_DEPTH_COUNT. + * + * See the explanation in brw_emit_query_begin(). + */ void brw_emit_query_end(struct brw_context *brw) { @@ -481,6 +603,11 @@ brw_query_counter(struct gl_context *ctx, struct gl_query_object *q) write_timestamp(intel, query->bo, 0); } +/** + * Read the TIMESTAMP register immediately (in a non-pipelined fashion). + * + * This is used to implement the GetTimestamp() driver hook. + */ static uint64_t brw_get_timestamp(struct gl_context *ctx) { |