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Update logic to set environment for calls out to nvidia-smi #110

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merged 1 commit into from
May 7, 2024
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Update logic to set environment for calls out to nvidia-smi #110

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51 changes: 34 additions & 17 deletions cmd/nvidia-dra-plugin/nvlib.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,8 +31,9 @@ import (

type deviceLib struct {
nvdev.Interface
nvmllib nvml.Interface
nvidiaSMIPath string
nvmllib nvml.Interface
driverLibraryPath string
nvidiaSMIPath string
}

func newDeviceLib(driverRoot root) (*deviceLib, error) {
Expand All @@ -46,32 +47,40 @@ func newDeviceLib(driverRoot root) (*deviceLib, error) {
return nil, fmt.Errorf("failed to locate nvidia-smi: %w", err)
}

// In order for nvidia-smi to run, we need to set the PATH to the parent of
// the nvidia-smi executable and update LD_PRELOAD to include the path to
// libnvidia-ml.so.1
updatePathListEnvvar("LD_PRELOAD", driverLibraryPath)
updatePathListEnvvar("PATH", filepath.Dir(nvidiaSMIPath))

// We construct an NVML library specifying the path to libnvidia-ml.so.1
// explicitly so that we don't have to rely on the library path.
nvmllib := nvml.New(
nvml.WithLibraryPath(driverLibraryPath),
)
d := deviceLib{
Interface: nvdev.New(nvdev.WithNvml(nvmllib)),
nvmllib: nvmllib,
nvidiaSMIPath: nvidiaSMIPath,
Interface: nvdev.New(nvdev.WithNvml(nvmllib)),
nvmllib: nvmllib,
driverLibraryPath: driverLibraryPath,
nvidiaSMIPath: nvidiaSMIPath,
}
return &d, nil
}

// updatePathListEnvvar prepends a specified list of strings to a specified envvar.
func updatePathListEnvvar(envvar string, prepend ...string) {
// prependPathListEnvvar prepends a specified list of strings to a specified envvar and returns its value.
func prependPathListEnvvar(envvar string, prepend ...string) string {
if len(prepend) == 0 {
return
return os.Getenv(envvar)
}
current := filepath.SplitList(os.Getenv(envvar))
os.Setenv(envvar, strings.Join(append(prepend, current...), string(filepath.ListSeparator)))
return strings.Join(append(prepend, current...), string(filepath.ListSeparator))
}

// setOrOverrideEnvvar adds or updates an envar to the list of specified envvars and returns it.
func setOrOverrideEnvvar(envvars []string, key, value string) []string {
var updated []string
for _, envvar := range envvars {
pair := strings.SplitN(envvar, "=", 2)
if pair[0] == key {
continue
}
updated = append(updated, envvar)
}
return append(updated, fmt.Sprintf("%s=%s", key, value))
}

func (l deviceLib) Init() error {
Expand Down Expand Up @@ -481,10 +490,14 @@ func walkMigDevices(d nvml.Device, f func(i int, d nvml.Device) error) error {
func (l deviceLib) setTimeSlice(uuids []string, timeSlice int) error {
for _, uuid := range uuids {
cmd := exec.Command(
"nvidia-smi",
l.nvidiaSMIPath,
"compute-policy",
"-i", uuid,
"--set-timeslice", fmt.Sprintf("%d", timeSlice))

// In order for nvidia-smi to run, we need update LD_PRELOAD to include the path to libnvidia-ml.so.1.
cmd.Env = setOrOverrideEnvvar(os.Environ(), "LD_PRELOAD", prependPathListEnvvar("LD_PRELOAD", l.driverLibraryPath))

output, err := cmd.CombinedOutput()
if err != nil {
klog.Errorf("\n%v", string(output))
Expand All @@ -497,9 +510,13 @@ func (l deviceLib) setTimeSlice(uuids []string, timeSlice int) error {
func (l deviceLib) setComputeMode(uuids []string, mode string) error {
for _, uuid := range uuids {
cmd := exec.Command(
"nvidia-smi",
l.nvidiaSMIPath,
"-i", uuid,
"-c", mode)

// In order for nvidia-smi to run, we need update LD_PRELOAD to include the path to libnvidia-ml.so.1.
cmd.Env = setOrOverrideEnvvar(os.Environ(), "LD_PRELOAD", prependPathListEnvvar("LD_PRELOAD", l.driverLibraryPath))

output, err := cmd.CombinedOutput()
if err != nil {
klog.Errorf("\n%v", string(output))
Expand Down