Add "fake-mode" option to GPU plugin for scalability testing

Devices can be faked for scalability testing when non-standard paths
are used (container runtimes hard-code some checks for standard
/dev & /sys paths which need to be avoided when faking devices).

If one wants to run both normal GPU plugin and faked one in same
cluster, all nodes providing fake "i915" resources should be labeled
differently from ones with real GPU plugin + devices, so that real GPU
workloads can be limited to correct nodes with a suitable
nodeSelector.

Signed-off-by: Eero Tamminen <[email protected]>

Author: eero-t

cmd/gpu_plugin/gpu_plugin.go

@@ -1,4 +1,4 @@
-// Copyright 2017-2021 Intel Corporation. All Rights Reserved.
+// Copyright 2017-2022 Intel Corporation. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -367,8 +367,10 @@ func (dp *devicePlugin) Allocate(request *pluginapi.AllocateRequest) (*pluginapi
 }
 
 func main() {
+	var prefix string
 	var opts cliOptions
 
+	flag.StringVar(&fprefix, "fake-mode", "", "Prefix for devfs & sysfs paths")
 	flag.BoolVar(&opts.enableMonitoring, "enable-monitoring", false, "whether to enable 'i915_monitoring' (= all GPUs) resource")
 	flag.BoolVar(&opts.resourceManagement, "resource-manager", false, "fractional GPU resource management")
 	flag.IntVar(&opts.sharedDevNum, "shared-dev-num", 1, "number of containers sharing the same GPU device")
@@ -393,7 +395,15 @@ func main() {
 
 	klog.V(1).Infof("GPU device plugin started with %s preferred allocation policy", opts.preferredAllocationPolicy)
 
-	plugin := newDevicePlugin(sysfsDrmDirectory, devfsDriDirectory, opts)
+	var sysfs, devfs string
+	if prefix != "" {
+		sysfs = prefix + sysfsDrmDirectory
+		devfs = prefix + devfsDriDirectory
+	} else {
+		sysfs = sysfsDrmDirectory
+		devfs = devfsDriDirectory
+	}
+	plugin := newDevicePlugin(sysfs, devfs, opts)
 	manager := dpapi.NewManager(namespace, plugin)
 	manager.Run()
 }