Merge pull request #19 from gomlx/cuda_check

Improved documentation on Nvidia GPU card detection, and error messag…

.github/workflows/go.yaml

@@ -1,7 +1,7 @@
 # Tests only run with --short, since the full tests involve downloading datasets
-# and would be too costly for a Github actions.
+# and would be too costly for a GitHub actions.
 # Locally in the development box it works because the datasets are cached.
-name: "Tests" # The name of the workflow that will appear on Github
+name: "Tests" # The name of the workflow that will appear on GitHub
 permissions:
   # read|write|none
   actions: read
@@ -59,12 +59,14 @@ jobs:
         go test ./xlabuilder/... ./pjrt/...
 
     - name: Go Coverage Badge
+      if: github.ref == 'refs/heads/main'
       uses: tj-actions/coverage-badge-go@v2
       with:
         green: 80
         filename: docs/coverage.out
 
     - name: Commit README.md changes
+      if: github.ref == 'refs/heads/main'
       run: |
         if git diff --quiet -- 'README.md' ; then
           echo "README.md not modified."
@@ -76,6 +78,7 @@ jobs:
         fi
 
     - name: Push Changes
+      if: github.ref == 'refs/heads/main'
       uses: ad-m/github-push-action@master
       with:
         github_token: ${{ github.token }}

docs/CHANGELOG.md

@@ -3,6 +3,9 @@
 * Added `install_linux_amd64_amazonlinux.sh` and pre-built libraries for amazonlinux (built using old glibc support).
 * Fixed installation scripts: s/sudo/$_SUDO. Also made them more verbose.
 * Removed dependency on `xargs` in installation script for Linux.
+* Improved documentation on Nvidia GPU card detection, and error message if not found. 
+* Updated GitHub action (`go.yaml`) to only change the README.md with the result of the change, if pushing to the
+  `main` branch.
 
 # v0.4.9 - 2024-11-25
 

pjrt/cuda.go

@@ -18,7 +18,9 @@ func isCuda(name string) bool {
 
 var hasNvidiaGPUCache *bool
 
-// hasNvidiaGPU tries to guess if there is an Nvidia GPU installed.
+// hasNvidiaGPU tries to guess if there is an actual Nvidia GPU installed (as opposed to only the drivers/PJRT
+// file installed, but no actual hardware).
+// It does that by checking for the presence of the device files in /dev/nvidia*.
 func hasNvidiaGPU() bool {
 	if hasNvidiaGPUCache != nil {
 		return *hasNvidiaGPUCache
@@ -29,6 +31,10 @@ func hasNvidiaGPU() bool {
 		return false
 	}
 	hasGPU := len(matches) > 0
+	if !hasGPU {
+		klog.Infof("No NVidia devices found matching \"/dev/nvidia*\", assuming there are no GPU cards installed in the system. " +
+			"To force the attempt to use the \"cuda\" PJRT, use its absolute path.")
+	}
 	hasNvidiaGPUCache = &hasGPU
 	return hasGPU
 }