intel/mda: Change the default output directory

Directories are named using the process name and PID to avoid overwriting dumps from
subsequent runs of the same application.

v2 (Caio): Use util_get_process_name().  Change to be default behavior.
           Old behavior still accessible via MDA_OUTPUT_DIR="." env var.

Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39125>

docs/drivers/anv.rst

@@ -421,12 +421,14 @@ paths in the shaders. To make use of this feature :
 
 3. Exit the application once enough data is captured
 
-4. Untar the ``anv-shaders.mda.tar`` file created in the directory the
-   application was launched (or in MDA_OUTPUT_DIR if it was set)
+4. Untar the ``anv-shaders.mda.tar`` file created in the ``NAME_PID_mda``
+   subdirectory, where ``NAME`` is the process name and ``PID`` is the process
+   ID. Set ``MDA_OUTPUT_DIR=.`` to create the file in the directory the
+   application was launched instead.
 
 .. code-block:: sh
 
-   mesa % tar xfv anv-shaders.mda.tar
+   mesa % tar xfv my_app_12345_mda/anv-shaders.mda.tar
 
 5. Look at the hot spots with ``intel_eu_stall_viewer`` :
 

docs/envvars.rst

@@ -913,7 +913,10 @@ Intel driver environment variables
 .. envvar:: MDA_OUTPUT_DIR
 
    Directory where the mda.tar files generated when using INTEL_DEBUG=mda or ANV_DEBUG=shader-dump are
-   going to be written to.  If not set, use the current directory.
+   going to be written to. If set, use that directory. If not set, create and
+   use a ``NAME_PID_mda`` subdirectory, where ``NAME`` is the process name and
+   ``PID`` is the process ID. If directory creation fails, use the current
+   directory.
 
 .. envvar:: MDA_PREFIX
 

src/intel/mda/debug_archiver.c

@@ -9,6 +9,7 @@
 #include "tar.h"
 #include "util/ralloc.h"
 #include "util/u_debug.h"
+#include "util/u_process.h"
 
 #include <string.h>
 #include <sys/stat.h>
@@ -25,7 +26,7 @@ struct debug_archiver
    char *mda_dir_in_archive;
 };
 
-DEBUG_GET_ONCE_OPTION(mda_output_dir, "MDA_OUTPUT_DIR", ".")
+DEBUG_GET_ONCE_OPTION(mda_output_dir, "MDA_OUTPUT_DIR", "")
 DEBUG_GET_ONCE_OPTION(mda_prefix, "MDA_PREFIX", NULL)
 DEBUG_GET_ONCE_OPTION(mda_filter, "MDA_FILTER", NULL)
 
@@ -81,6 +82,14 @@ debug_archiver_open(void *mem_ctx, const char *name, const char *info)
    const char *output_dir = debug_get_option_mda_output_dir();
    const char *prefix     = debug_get_option_mda_prefix();
 
+   if (!output_dir || !*output_dir) {
+      const char *process_name = util_get_process_name();
+      if (!process_name || !*process_name)
+         process_name = "unknown_process";
+
+      output_dir = ralloc_asprintf(da, "./%s_%d_mda", process_name, getpid());
+   }
+
    if (!ensure_output_dir(output_dir)) {
       /* Fallback to current directory on failure. */
       output_dir = ".";