GCN, nvptx: Errors during device probing are fatal

Currently, we silently disable libgomp GCN and nvptx plugins/devices in
presence of certain error conditions during device probing, thus typically
silently resorting to host-fallback execution.  Make such errors fatal, similar
as for any other device access later on, so that we early and reliably notice
when things go wrong.  (Keep just two cases non-fatal: (a) libgomp GCN or nvptx
plugins are available but 'libhsa-runtime64.so.1' or 'libcuda.so.1' are not,
and (b) those are available, but the corresponding devices are not.)

This resolves the issue that we've got execution test cases unexpectedly
PASSing, despite:

    libgomp: GCN fatal error: Run-time could not be initialized
    Runtime message: HSA_STATUS_ERROR_OUT_OF_RESOURCES: The runtime failed to allocate the necessary resources. This error may also occur when the core runtime library needs to spawn threads or create internal OS-specific events.

..., and therefore they were not offloaded to the GCN device, but ran in
host-fallback execution mode.  What happend in that scenario is that in
'init_hsa_context' during the initial 'GOMP_OFFLOAD_get_num_devices' we ran
into 'HSA_STATUS_ERROR_OUT_OF_RESOURCES', but it wasn't fatal, but just
silently disabled the libgomp plugin/device.

Especially "entertaining" were cases where such unintended host-fallback
execution happened during effective-target checks like
'offload_device_available' (host-fallback execution there meaning: no offload
device available), but actual test cases then were running with an offload
device available, and therefore mis-configured.

	include/
	* cuda/cuda.h (CUresult): Add 'CUDA_ERROR_NO_DEVICE'.
	libgomp/
	* plugin/plugin-gcn.c (init_hsa_context): Add and handle
	'bool probe' parameter.  Adjust all users; errors during device
	probing are fatal.
	* plugin/plugin-nvptx.c (nvptx_get_num_devices): Aside from
	'CUDA_ERROR_NO_DEVICE', errors during device probing are fatal.

diff --git a/include/cuda/cuda.h b/include/cuda/cuda.h
index 114aba4e074faf93138a01690e6c1267a9f77847..0dca4b3a5c0b055dcc13ceef7b2559c22fd73a36 100644 (file)
--- a/include/cuda/cuda.h
+++ b/include/cuda/cuda.h
@@ -57,6 +57,7 @@ typedef enum {
   CUDA_ERROR_OUT_OF_MEMORY = 2,
   CUDA_ERROR_NOT_INITIALIZED = 3,
   CUDA_ERROR_DEINITIALIZED = 4,
+  CUDA_ERROR_NO_DEVICE = 100,
   CUDA_ERROR_INVALID_CONTEXT = 201,
   CUDA_ERROR_INVALID_HANDLE = 400,
   CUDA_ERROR_NOT_FOUND = 500,

diff --git a/libgomp/plugin/plugin-gcn.c b/libgomp/plugin/plugin-gcn.c
index 1d183b61ca4f7302b77cb714e42c3c1ca801bf81..27947801ccda7c4e99d13406f3b1456c43450389 100644 (file)
--- a/libgomp/plugin/plugin-gcn.c
+++ b/libgomp/plugin/plugin-gcn.c
@@ -1513,10 +1513,12 @@ assign_agent_ids (hsa_agent_t agent, void *data)
 }
 
 /* Initialize hsa_context if it has not already been done.
-   Return TRUE on success.  */
+   If !PROBE: returns TRUE on success.
+   If PROBE: returns TRUE on success or if the plugin/device shall be silently
+   ignored, and otherwise emits an error and returns FALSE.  */
 
 static bool
-init_hsa_context (void)
+init_hsa_context (bool probe)
 {
   hsa_status_t status;
   int agent_index = 0;
@@ -1531,7 +1533,7 @@ init_hsa_context (void)
        GOMP_PLUGIN_fatal ("%s\n", msg);
       else
        GCN_WARNING ("%s\n", msg);
-      return false;
+      return probe ? true : false;
     }
   status = hsa_fns.hsa_init_fn ();
   if (status != HSA_STATUS_SUCCESS)
@@ -3337,8 +3339,8 @@ GOMP_OFFLOAD_version (void)
 int
 GOMP_OFFLOAD_get_num_devices (unsigned int omp_requires_mask)
 {
-  if (!init_hsa_context ())
-    return 0;
+  if (!init_hsa_context (true))
+    exit (EXIT_FAILURE);
   /* Return -1 if no omp_requires_mask cannot be fulfilled but
      devices were present.  */
   if (hsa_context.agent_count > 0
@@ -3355,7 +3357,7 @@ GOMP_OFFLOAD_get_num_devices (unsigned int omp_requires_mask)
 bool
 GOMP_OFFLOAD_init_device (int n)
 {
-  if (!init_hsa_context ())
+  if (!init_hsa_context (false))
     return false;
   if (n >= hsa_context.agent_count)
     {

diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c
index ced6e014ecee2b076a1b57e6188ca67725d89a68..5aad3448a8db5cd9821ec23ab9354994586881ab 100644 (file)
--- a/libgomp/plugin/plugin-nvptx.c
+++ b/libgomp/plugin/plugin-nvptx.c
@@ -604,12 +604,14 @@ nvptx_get_num_devices (void)
       CUresult r = CUDA_CALL_NOCHECK (cuInit, 0);
       /* This is not an error: e.g. we may have CUDA libraries installed but
          no devices available.  */
-      if (r != CUDA_SUCCESS)
+      if (r == CUDA_ERROR_NO_DEVICE)
        {
          GOMP_PLUGIN_debug (0, "Disabling nvptx offloading; cuInit: %s\n",
                             cuda_error (r));
          return 0;
        }
+      else if (r != CUDA_SUCCESS)
+       GOMP_PLUGIN_fatal ("cuInit error: %s", cuda_error (r));
     }
 
   CUDA_CALL_ASSERT (cuDeviceGetCount, &n);