Support installation on Linux4Tegraecrts25-ae

- Use alternate path if nvidia-cuda-mps-control is not found.
- Work-around missing CUDA_MPS_PIPE_DIRECTORY default in L4T.
- Install to L4T-specific paths if they exist.

Note that CUDA_MPS_PIPE_DIRECTORY must be manually set by the user
on L4T systems before they can call nvidia-cuda-mps-control, or to
have to have non-nvtaskset-launched applications run with MPS.

Tested on Jetson AGX Orin with L4T 36.3.0 and cuda-compat-12-6.

1 files changed, 23 insertions, 4 deletions

diff --git a/nvtaskset.c b/nvtaskset.c
index 5cf3a85..3a50221 100644
--- a/nvtaskset.c
+++ b/nvtaskset.c
@@ -359,16 +359,34 @@ static error_t arg_parser(int key, char* arg, struct argp_state *state){
                                 else
                                         printf("PID %d's current TPC affinity mask: 0x%.0lx%016lx\n", target_pid, (uint64_t)(enable_mask >> 64), (uint64_t)enable_mask);
                         } else if (is_cmd) {
+                                if (!getenv("CUDA_MPS_PIPE_DIRECTORY")) {
+                                        // Pipe directory is not set by default on L4T aarch64
+                                        putenv("CUDA_MPS_PIPE_DIRECTORY=/tmp/nvidia-mps");
+                                }
                                 // start MPS (as needed)
                                 if (!libsmctrl_is_mps_running()) {
                                         fprintf(stderr, "nvtaskset: MPS control deamon does not appear to be running. Automatically starting...\n");
+                                        // TODO: Mute the error message if this command isn't found?
                                         int ret = system("nvidia-cuda-mps-control -d");
+                                        // TODO: Fall back to full x86_64 install location?
+                                        // Fall back to full L4T aarch64 install location
+                                        if (ret == 0x7f00) {
+                                                // nvidia-cuda-mps-control needs nvidia-cuda-mps-server to be on PATH
+                                                char *old_path = getenv("PATH");
+                                                char *new_path;
+                                                if (old_path)
+                                                        asprintf(&new_path, "PATH=/usr/local/cuda/compat/:%s", old_path);
+                                                else
+                                                        new_path = "PATH=/usr/local/cuda/compat/";
+                                                putenv(new_path);
+                                                ret = system("nvidia-cuda-mps-control -d");
+                                                // TODO: Put this warning after error checking
+                                                fprintf(stderr, "nvtaskset: Warning: Set the CUDA_MPS_PIPE_DIRECTORY environment variable to /tmp/nvidia-mps to ensure that subsequently launched tasks associate with MPS on L4T systems!\n");
+                                        }
                                         if (ret == -1)
                                                 error(1, errno, "Unable to run subshell to start MPS");
-                                        if (ret == 1) {
-                                                fprintf(stderr, "nvtaskset: Error starting MPS control deamon. Terminating...\n");
-                                                return 1;
-                                        }
+                                        else if (ret)
+                                                error(1, 0, "Error starting MPS control deamon. Terminating...");
                                         fprintf(stderr, "nvtaskset: Done. Use \"echo quit | nvidia-cuda-mps-control\" to terminate it later as desired.\n");
                                 }
                                 // launch subprocess
@@ -377,6 +395,7 @@ static error_t arg_parser(int key, char* arg, struct argp_state *state){
                                 snprintf(mask_str, 36, "~0x%.0lx%016lx", (uint64_t)(mask >> 64), (uint64_t)mask);
                                 setenv("LIBSMCTRL_MASK", mask_str, 1);
                                 // Start task
+                                // TODO: Check that the loader is configured to find the corrrect libcuda.so.1
                                 execvp(sub_argv[0], sub_argv);
                                 error(1, errno, "Unable to launch task '%s'", sub_argv[0]);
                         } else {