Mesa (main): util/u_trace/perfetto: add new env variable to enable perfetto

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Module: Mesa
Branch: main
Commit: 698343edc57619de5bb85ce1f208633b96e2fea8
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=698343edc57619de5bb85ce1f208633b96e2fea8

Author: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Date:   Mon Nov 22 12:56:20 2021 +0200

util/u_trace/perfetto: add new env variable to enable perfetto

When using the Vulkan API, command buffers can be recorded way before
perfetto is enabled. This can be problematic if you want already
recorded command buffers to produce traces.

This new environment variable makes perfetto enabled internally so
that command buffers are recorded with timestamps, even though no
perfetto recording happens.

v2: rename to GPU_TRACE_INSTRUMENT (Rob)

v3: Move instrumentation check to generated headers (Danylo)
    Decouple instrumentation enabling from tracing (Danylo)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Reviewed-by: Danylo Piliaiev <dpiliaiev at igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13911>

---

 docs/perfetto.rst             | 16 ++++++++++++++++
 src/freedreno/vulkan/tu_drm.c |  2 +-
 src/util/perf/u_trace.c       |  9 +++++++--
 src/util/perf/u_trace.h       | 14 +++++++++++++-
 src/util/perf/u_trace.py      |  4 ++--
 5 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/docs/perfetto.rst b/docs/perfetto.rst
index dd78db564b4..17379e6f770 100644
--- a/docs/perfetto.rst
+++ b/docs/perfetto.rst
@@ -104,6 +104,22 @@ the steps above :
 
    # Back in the perfetto tmux, press enter to start the capture
 
+Vulkan data sources
+~~~~~~~~~~~~~~~~~~~
+
+The Vulkan API gives the application control over recording of command
+buffers as well as when they are submitted to the hardware. As a
+consequence, we need to ensure command buffers are properly
+instrumented for the perfetto driver data sources prior to Perfetto
+actually collecting traces.
+
+This can be achieved by setting the ``GPU_TRACE_INSTRUMENT``
+environment variable before starting a Vulkan application :
+
+.. code-block:: console
+
+   GPU_TRACE_INSTRUMENT=1 ./build/my_vulkan_app
+
 Driver Specifics
 ~~~~~~~~~~~~~~~~
 
diff --git a/src/freedreno/vulkan/tu_drm.c b/src/freedreno/vulkan/tu_drm.c
index ae8c037beb9..591115e738e 100644
--- a/src/freedreno/vulkan/tu_drm.c
+++ b/src/freedreno/vulkan/tu_drm.c
@@ -950,7 +950,7 @@ tu_queue_submit_create_locked(struct tu_queue *queue,
       }
    }
 
-   bool u_trace_enabled = u_trace_context_tracing(&queue->device->trace_context);
+   bool u_trace_enabled = u_trace_context_actively_tracing(&queue->device->trace_context);
    bool has_trace_points = false;
 
    uint32_t entry_count = 0;
diff --git a/src/util/perf/u_trace.c b/src/util/perf/u_trace.c
index 1252897688b..aae22856c20 100644
--- a/src/util/perf/u_trace.c
+++ b/src/util/perf/u_trace.c
@@ -38,6 +38,8 @@
 #define TIMESTAMP_BUF_SIZE 0x1000
 #define TRACES_PER_CHUNK   (TIMESTAMP_BUF_SIZE / sizeof(uint64_t))
 
+bool ut_trace_instrument;
+
 #ifdef HAVE_PERFETTO
 int ut_perfetto_enabled;
 
@@ -217,6 +219,7 @@ get_chunk(struct u_trace *ut, size_t payload_size)
    return chunk;
 }
 
+DEBUG_GET_ONCE_BOOL_OPTION(trace_instrument, "GPU_TRACE_INSTRUMENT", false)
 DEBUG_GET_ONCE_BOOL_OPTION(trace, "GPU_TRACE", false)
 DEBUG_GET_ONCE_FILE_OPTION(trace_file, "GPU_TRACEFILE", NULL, "w")
 
@@ -232,6 +235,8 @@ get_tracefile(void)
          tracefile = stdout;
       }
 
+      ut_trace_instrument = debug_get_option_trace_instrument();
+
       firsttime = false;
    }
 
@@ -281,7 +286,7 @@ u_trace_context_init(struct u_trace_context *utctx,
    list_add(&utctx->node, &ctx_list);
 #endif
 
-   if (!u_trace_context_tracing(utctx))
+   if (!u_trace_context_actively_tracing(utctx))
       return;
 
    queue_init(utctx);
@@ -425,7 +430,7 @@ u_trace_init(struct u_trace *ut, struct u_trace_context *utctx)
 {
    ut->utctx = utctx;
    list_inithead(&ut->trace_chunks);
-   ut->enabled = u_trace_context_tracing(utctx);
+   ut->enabled = u_trace_context_instrumenting(utctx);
 }
 
 void
diff --git a/src/util/perf/u_trace.h b/src/util/perf/u_trace.h
index 7e3f7aaa2e2..8f21c4941dc 100644
--- a/src/util/perf/u_trace.h
+++ b/src/util/perf/u_trace.h
@@ -267,6 +267,12 @@ void u_trace_disable_event_range(struct u_trace_iterator begin_it,
  */
 void u_trace_flush(struct u_trace *ut, void *flush_data, bool free_data);
 
+/**
+ * Whether command buffers should be instrumented even if not collecting
+ * traces.
+ */
+extern bool ut_trace_instrument;
+
 #ifdef HAVE_PERFETTO
 extern int ut_perfetto_enabled;
 
@@ -277,11 +283,17 @@ void u_trace_perfetto_stop(void);
 #endif
 
 static inline bool
-u_trace_context_tracing(struct u_trace_context *utctx)
+u_trace_context_actively_tracing(struct u_trace_context *utctx)
 {
    return !!utctx->out || (ut_perfetto_enabled > 0);
 }
 
+static inline bool
+u_trace_context_instrumenting(struct u_trace_context *utctx)
+{
+   return !!utctx->out || ut_trace_instrument || (ut_perfetto_enabled > 0);
+}
+
 #ifdef  __cplusplus
 }
 #endif
diff --git a/src/util/perf/u_trace.py b/src/util/perf/u_trace.py
index f80b253d899..374ec790c52 100644
--- a/src/util/perf/u_trace.py
+++ b/src/util/perf/u_trace.py
@@ -212,9 +212,9 @@ static inline void trace_${trace_name}(struct u_trace *ut, void *cs
 %    endfor
 ) {
 %    if trace.tp_perfetto is not None:
-   if (!unlikely(ut->enabled || ut_perfetto_enabled))
+   if (!unlikely(ut->enabled || ut_trace_instrument || ut_perfetto_enabled))
 %    else:
-   if (!unlikely(ut->enabled))
+   if (!unlikely(ut->enabled || ut_trace_instrument))
 %    endif
       return;
    __trace_${trace_name}(ut, cs