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libcontainer: intelrdt: add user-friendly diagnostics for Intel RDT operation errors #1913

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Merged
caniszczyk merged 1 commit into from
Oct 25, 2018
Merged

libcontainer: intelrdt: add user-friendly diagnostics for Intel RDT operation errors #1913

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46 changes: 41 additions & 5 deletions libcontainer/intelrdt/intelrdt.go
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Original file line number Diff line number Diff line change
Expand Up @@ -439,6 +439,22 @@ func getMemBwInfo() (*MemBwInfo, error) {
return memBwInfo, nil
}

// Get diagnostics for last filesystem operation error from file info/last_cmd_status
func getLastCmdStatus() (string, error) {
rootPath, err := getIntelRdtRoot()
if err != nil {
return "", err
}

path := filepath.Join(rootPath, "info")
lastCmdStatus, err := getIntelRdtParamString(path, "last_cmd_status")
if err != nil {
return "", err
}
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@hqhq hqhq Oct 22, 2018

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What if the system doesn't support "last_cmd_status", is it gonna fall back to use the error we got in getIntelRdtParamString? Doesn't sound quite right.

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@xiaochenshen xiaochenshen Oct 22, 2018

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@hqhq

Thank you for kind code review!

This change could handle the case when system doesn't support "last_cmd_status":

Firstly, getLastCmdStatus() returns the error which we get from getIntelRdtParamString() to the caller NewLastCmdError().

In NewLastCmdError(), parameter 'err' is the original error. 'err1' is the error returns from getLastCmdStatus().

  1. err1 != nil indicates that we don't support "last_cmd_status". We just return original 'err' directly.
  2. Only when err1 == nil, which indicates that we support "last_cmd_status", we will call overloaded function Error() to append extra diagnostics information to original 'err'.

See more details in NewLastCmdError():

func NewLastCmdError(err error) error {
	lastCmdStatus, err1 := getLastCmdStatus()
	if err1 == nil {
		return &LastCmdError{
			LastCmdStatus: lastCmdStatus,
			Err:           err,
		}
	}
	return err
}

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@hqhq hqhq Oct 22, 2018

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OK, I misread that, thanks for explanation.


return lastCmdStatus, nil
}

// WriteIntelRdtTasks writes the specified pid into the "tasks" file
func WriteIntelRdtTasks(dir string, pid int) error {
if dir == "" {
Expand Down Expand Up @@ -637,21 +653,21 @@ func (m *IntelRdtManager) Set(container *configs.Config) error {
// Write a single joint schema string to schemata file
if l3CacheSchema != "" && memBwSchema != "" {
if err := writeFile(path, "schemata", l3CacheSchema+"\n"+memBwSchema); err != nil {
return err
return NewLastCmdError(err)
}
}

// Write only L3 cache schema string to schemata file
if l3CacheSchema != "" && memBwSchema == "" {
if err := writeFile(path, "schemata", l3CacheSchema); err != nil {
return err
return NewLastCmdError(err)
}
}

// Write only memory bandwidth schema string to schemata file
if l3CacheSchema == "" && memBwSchema != "" {
if err := writeFile(path, "schemata", memBwSchema); err != nil {
return err
return NewLastCmdError(err)
}
}
}
Expand All @@ -662,11 +678,11 @@ func (m *IntelRdtManager) Set(container *configs.Config) error {
func (raw *intelRdtData) join(id string) (string, error) {
path := filepath.Join(raw.root, id)
if err := os.MkdirAll(path, 0755); err != nil {
return "", err
return "", NewLastCmdError(err)
}

if err := WriteIntelRdtTasks(path, raw.pid); err != nil {
return "", err
return "", NewLastCmdError(err)
}
return path, nil
}
Expand All @@ -692,3 +708,23 @@ func IsNotFound(err error) bool {
_, ok := err.(*NotFoundError)
return ok
}

type LastCmdError struct {
LastCmdStatus string
Err error
}

func (e *LastCmdError) Error() string {
return fmt.Sprintf(e.Err.Error() + ", last_cmd_status: " + e.LastCmdStatus)
}

func NewLastCmdError(err error) error {
lastCmdStatus, err1 := getLastCmdStatus()
if err1 == nil {
return &LastCmdError{
LastCmdStatus: lastCmdStatus,
Err: err,
}
}
return err
}