procfs - ActiveState ActiveGo 1.8
...

Package procfs

import "github.com/prometheus/procfs"
Overview
Index
Subdirectories

Overview ▾

Package procfs provides functions to retrieve system, kernel and process metrics from the pseudo-filesystem proc.

Example:

package main

import (
	"fmt"
	"log"

	"github.com/prometheus/procfs"
)

func main() {
	p, err := procfs.Self()
	if err != nil {
		log.Fatalf("could not get process: %s", err)
	}

	stat, err := p.NewStat()
	if err != nil {
		log.Fatalf("could not get process stat: %s", err)
	}

	fmt.Printf("command:  %s\n", stat.Comm)
	fmt.Printf("cpu time: %fs\n", stat.CPUTime())
	fmt.Printf("vsize:    %dB\n", stat.VirtualMemory())
	fmt.Printf("rss:      %dB\n", stat.ResidentMemory())
}

Index ▾

Constants
func NewBuddyInfo() ([]BuddyInfo, error)
func NewIPVSBackendStatus() ([]IPVSBackendStatus, error)
type BuddyInfo
type CPUStat
type FS
    func NewFS(mountPoint string) (FS, error)
    func (fs FS) AllProcs() (Procs, error)
    func (fs FS) NewBuddyInfo() ([]BuddyInfo, error)
    func (fs FS) NewIPVSBackendStatus() ([]IPVSBackendStatus, error)
    func (fs FS) NewIPVSStats() (IPVSStats, error)
    func (fs FS) NewProc(pid int) (Proc, error)
    func (fs FS) NewStat() (Stat, error)
    func (fs FS) NewXfrmStat() (XfrmStat, error)
    func (fs FS) ParseMDStat() (mdstates []MDStat, err error)
    func (fs FS) Path(p ...string) string
    func (fs FS) Self() (Proc, error)
    func (fs FS) XFSStats() (*xfs.Stats, error)
type IPVSBackendStatus
type IPVSStats
    func NewIPVSStats() (IPVSStats, error)
type MDStat
type Mount
type MountStats
type MountStatsNFS
type NFSBytesStats
type NFSEventsStats
type NFSOperationStats
type NFSTransportStats
type Proc
    func NewProc(pid int) (Proc, error)
    func Self() (Proc, error)
    func (p Proc) CmdLine() ([]string, error)
    func (p Proc) Comm() (string, error)
    func (p Proc) Executable() (string, error)
    func (p Proc) FileDescriptorTargets() ([]string, error)
    func (p Proc) FileDescriptors() ([]uintptr, error)
    func (p Proc) FileDescriptorsLen() (int, error)
    func (p Proc) MountStats() ([]*Mount, error)
    func (p Proc) NewIO() (ProcIO, error)
    func (p Proc) NewLimits() (ProcLimits, error)
    func (p Proc) NewStat() (ProcStat, error)
type ProcIO
type ProcLimits
type ProcStat
    func (s ProcStat) CPUTime() float64
    func (s ProcStat) ResidentMemory() int
    func (s ProcStat) StartTime() (float64, error)
    func (s ProcStat) VirtualMemory() int
type Procs
    func AllProcs() (Procs, error)
    func (p Procs) Len() int
    func (p Procs) Less(i, j int) bool
    func (p Procs) Swap(i, j int)
type SoftIRQStat
type Stat
    func NewStat() (Stat, error)
type XfrmStat
    func NewXfrmStat() (XfrmStat, error)

Package files

buddyinfo.go doc.go fs.go ipvs.go mdstat.go mountstats.go proc.go proc_io.go proc_limits.go proc_stat.go stat.go xfrm.go

Constants

DefaultMountPoint is the common mount point of the proc filesystem.

const DefaultMountPoint = "/proc"

func NewBuddyInfo

func NewBuddyInfo() ([]BuddyInfo, error)

NewBuddyInfo reads the buddyinfo statistics.

func NewIPVSBackendStatus

func NewIPVSBackendStatus() ([]IPVSBackendStatus, error)

NewIPVSBackendStatus reads and returns the status of all (virtual,real) server pairs.

type BuddyInfo

A BuddyInfo is the details parsed from /proc/buddyinfo. The data is comprised of an array of free fragments of each size. The sizes are 2^n*PAGE_SIZE, where n is the array index.

type BuddyInfo struct {
    Node  string
    Zone  string
    Sizes []float64
}

type CPUStat

CPUStat shows how much time the cpu spend in various stages.

type CPUStat struct {
    User      float64
    Nice      float64
    System    float64
    Idle      float64
    Iowait    float64
    IRQ       float64
    SoftIRQ   float64
    Steal     float64
    Guest     float64
    GuestNice float64
}

type FS

FS represents the pseudo-filesystem proc, which provides an interface to kernel data structures.

type FS string

func NewFS

func NewFS(mountPoint string) (FS, error)

NewFS returns a new FS mounted under the given mountPoint. It will error if the mount point can't be read.

func (FS) AllProcs

func (fs FS) AllProcs() (Procs, error)

AllProcs returns a list of all currently available processes.

func (FS) NewBuddyInfo

func (fs FS) NewBuddyInfo() ([]BuddyInfo, error)

NewBuddyInfo reads the buddyinfo statistics from the specified `proc` filesystem.

func (FS) NewIPVSBackendStatus

func (fs FS) NewIPVSBackendStatus() ([]IPVSBackendStatus, error)

NewIPVSBackendStatus reads and returns the status of all (virtual,real) server pairs from the specified `proc` filesystem.

func (FS) NewIPVSStats

func (fs FS) NewIPVSStats() (IPVSStats, error)

NewIPVSStats reads the IPVS statistics from the specified `proc` filesystem.

func (FS) NewProc

func (fs FS) NewProc(pid int) (Proc, error)

NewProc returns a process for the given pid.

func (FS) NewStat

func (fs FS) NewStat() (Stat, error)

NewStat returns an information about current kernel/system statistics.

func (FS) NewXfrmStat

func (fs FS) NewXfrmStat() (XfrmStat, error)

NewXfrmStat reads the xfrm_stat statistics from the 'proc' filesystem.

func (FS) ParseMDStat

func (fs FS) ParseMDStat() (mdstates []MDStat, err error)

ParseMDStat parses an mdstat-file and returns a struct with the relevant infos.

func (FS) Path

func (fs FS) Path(p ...string) string

Path returns the path of the given subsystem relative to the procfs root.

func (FS) Self

func (fs FS) Self() (Proc, error)

Self returns a process for the current process.

func (FS) XFSStats

func (fs FS) XFSStats() (*xfs.Stats, error)

XFSStats retrieves XFS filesystem runtime statistics.

type IPVSBackendStatus

IPVSBackendStatus holds current metrics of one virtual / real address pair.

type IPVSBackendStatus struct {
    // The local (virtual) IP address.
    LocalAddress net.IP
    // The local (virtual) port.
    LocalPort uint16
    // The local firewall mark
    LocalMark string
    // The transport protocol (TCP, UDP).
    Proto string
    // The remote (real) IP address.
    RemoteAddress net.IP
    // The remote (real) port.
    RemotePort uint16
    // The current number of active connections for this virtual/real address pair.
    ActiveConn uint64
    // The current number of inactive connections for this virtual/real address pair.
    InactConn uint64
    // The current weight of this virtual/real address pair.
    Weight uint64
}

type IPVSStats

IPVSStats holds IPVS statistics, as exposed by the kernel in `/proc/net/ip_vs_stats`.

type IPVSStats struct {
    // Total count of connections.
    Connections uint64
    // Total incoming packages processed.
    IncomingPackets uint64
    // Total outgoing packages processed.
    OutgoingPackets uint64
    // Total incoming traffic.
    IncomingBytes uint64
    // Total outgoing traffic.
    OutgoingBytes uint64
}

func NewIPVSStats

func NewIPVSStats() (IPVSStats, error)

NewIPVSStats reads the IPVS statistics.

type MDStat

MDStat holds info parsed from /proc/mdstat.

type MDStat struct {
    // Name of the device.
    Name string
    // activity-state of the device.
    ActivityState string
    // Number of active disks.
    DisksActive int64
    // Total number of disks the device consists of.
    DisksTotal int64
    // Number of blocks the device holds.
    BlocksTotal int64
    // Number of blocks on the device that are in sync.
    BlocksSynced int64
}

type Mount

A Mount is a device mount parsed from /proc/[pid]/mountstats.

type Mount struct {
    // Name of the device.
    Device string
    // The mount point of the device.
    Mount string
    // The filesystem type used by the device.
    Type string
    // If available additional statistics related to this Mount.
    // Use a type assertion to determine if additional statistics are available.
    Stats MountStats
}

type MountStats

A MountStats is a type which contains detailed statistics for a specific type of Mount.

type MountStats interface {
    // contains filtered or unexported methods
}

type MountStatsNFS

A MountStatsNFS is a MountStats implementation for NFSv3 and v4 mounts.

type MountStatsNFS struct {
    // The version of statistics provided.
    StatVersion string
    // The age of the NFS mount.
    Age time.Duration
    // Statistics related to byte counters for various operations.
    Bytes NFSBytesStats
    // Statistics related to various NFS event occurrences.
    Events NFSEventsStats
    // Statistics broken down by filesystem operation.
    Operations []NFSOperationStats
    // Statistics about the NFS RPC transport.
    Transport NFSTransportStats
}

type NFSBytesStats

A NFSBytesStats contains statistics about the number of bytes read and written by an NFS client to and from an NFS server.

type NFSBytesStats struct {
    // Number of bytes read using the read() syscall.
    Read uint64
    // Number of bytes written using the write() syscall.
    Write uint64
    // Number of bytes read using the read() syscall in O_DIRECT mode.
    DirectRead uint64
    // Number of bytes written using the write() syscall in O_DIRECT mode.
    DirectWrite uint64
    // Number of bytes read from the NFS server, in total.
    ReadTotal uint64
    // Number of bytes written to the NFS server, in total.
    WriteTotal uint64
    // Number of pages read directly via mmap()'d files.
    ReadPages uint64
    // Number of pages written directly via mmap()'d files.
    WritePages uint64
}

type NFSEventsStats

A NFSEventsStats contains statistics about NFS event occurrences.

type NFSEventsStats struct {
    // Number of times cached inode attributes are re-validated from the server.
    InodeRevalidate uint64
    // Number of times cached dentry nodes are re-validated from the server.
    DnodeRevalidate uint64
    // Number of times an inode cache is cleared.
    DataInvalidate uint64
    // Number of times cached inode attributes are invalidated.
    AttributeInvalidate uint64
    // Number of times files or directories have been open()'d.
    VFSOpen uint64
    // Number of times a directory lookup has occurred.
    VFSLookup uint64
    // Number of times permissions have been checked.
    VFSAccess uint64
    // Number of updates (and potential writes) to pages.
    VFSUpdatePage uint64
    // Number of pages read directly via mmap()'d files.
    VFSReadPage uint64
    // Number of times a group of pages have been read.
    VFSReadPages uint64
    // Number of pages written directly via mmap()'d files.
    VFSWritePage uint64
    // Number of times a group of pages have been written.
    VFSWritePages uint64
    // Number of times directory entries have been read with getdents().
    VFSGetdents uint64
    // Number of times attributes have been set on inodes.
    VFSSetattr uint64
    // Number of pending writes that have been forcefully flushed to the server.
    VFSFlush uint64
    // Number of times fsync() has been called on directories and files.
    VFSFsync uint64
    // Number of times locking has been attempted on a file.
    VFSLock uint64
    // Number of times files have been closed and released.
    VFSFileRelease uint64
    // Unknown.  Possibly unused.
    CongestionWait uint64
    // Number of times files have been truncated.
    Truncation uint64
    // Number of times a file has been grown due to writes beyond its existing end.
    WriteExtension uint64
    // Number of times a file was removed while still open by another process.
    SillyRename uint64
    // Number of times the NFS server gave less data than expected while reading.
    ShortRead uint64
    // Number of times the NFS server wrote less data than expected while writing.
    ShortWrite uint64
    // Number of times the NFS server indicated EJUKEBOX; retrieving data from
    // offline storage.
    JukeboxDelay uint64
    // Number of NFS v4.1+ pNFS reads.
    PNFSRead uint64
    // Number of NFS v4.1+ pNFS writes.
    PNFSWrite uint64
}

type NFSOperationStats

A NFSOperationStats contains statistics for a single operation.

type NFSOperationStats struct {
    // The name of the operation.
    Operation string
    // Number of requests performed for this operation.
    Requests uint64
    // Number of times an actual RPC request has been transmitted for this operation.
    Transmissions uint64
    // Number of times a request has had a major timeout.
    MajorTimeouts uint64
    // Number of bytes sent for this operation, including RPC headers and payload.
    BytesSent uint64
    // Number of bytes received for this operation, including RPC headers and payload.
    BytesReceived uint64
    // Duration all requests spent queued for transmission before they were sent.
    CumulativeQueueTime time.Duration
    // Duration it took to get a reply back after the request was transmitted.
    CumulativeTotalResponseTime time.Duration
    // Duration from when a request was enqueued to when it was completely handled.
    CumulativeTotalRequestTime time.Duration
}

type NFSTransportStats

A NFSTransportStats contains statistics for the NFS mount RPC requests and responses.

type NFSTransportStats struct {
    // The local port used for the NFS mount.
    Port uint64
    // Number of times the client has had to establish a connection from scratch
    // to the NFS server.
    Bind uint64
    // Number of times the client has made a TCP connection to the NFS server.
    Connect uint64
    // Duration (in jiffies, a kernel internal unit of time) the NFS mount has
    // spent waiting for connections to the server to be established.
    ConnectIdleTime uint64
    // Duration since the NFS mount last saw any RPC traffic.
    IdleTime time.Duration
    // Number of RPC requests for this mount sent to the NFS server.
    Sends uint64
    // Number of RPC responses for this mount received from the NFS server.
    Receives uint64
    // Number of times the NFS server sent a response with a transaction ID
    // unknown to this client.
    BadTransactionIDs uint64
    // A running counter, incremented on each request as the current difference
    // ebetween sends and receives.
    CumulativeActiveRequests uint64
    // A running counter, incremented on each request by the current backlog
    // queue size.
    CumulativeBacklog uint64

    // Maximum number of simultaneously active RPC requests ever used.
    MaximumRPCSlotsUsed uint64
    // A running counter, incremented on each request as the current size of the
    // sending queue.
    CumulativeSendingQueue uint64
    // A running counter, incremented on each request as the current size of the
    // pending queue.
    CumulativePendingQueue uint64
}

type Proc

Proc provides information about a running process.

type Proc struct {
    // The process ID.
    PID int
    // contains filtered or unexported fields
}

func NewProc

func NewProc(pid int) (Proc, error)

NewProc returns a process for the given pid under /proc.

func Self

func Self() (Proc, error)

Self returns a process for the current process read via /proc/self.

func (Proc) CmdLine

func (p Proc) CmdLine() ([]string, error)

CmdLine returns the command line of a process.

func (Proc) Comm

func (p Proc) Comm() (string, error)

Comm returns the command name of a process.

func (Proc) Executable

func (p Proc) Executable() (string, error)

Executable returns the absolute path of the executable command of a process.

func (Proc) FileDescriptorTargets

func (p Proc) FileDescriptorTargets() ([]string, error)

FileDescriptorTargets returns the targets of all file descriptors of a process. If a file descriptor is not a symlink to a file (like a socket), that value will be the empty string.

func (Proc) FileDescriptors

func (p Proc) FileDescriptors() ([]uintptr, error)

FileDescriptors returns the currently open file descriptors of a process.

func (Proc) FileDescriptorsLen

func (p Proc) FileDescriptorsLen() (int, error)

FileDescriptorsLen returns the number of currently open file descriptors of a process.

func (Proc) MountStats

func (p Proc) MountStats() ([]*Mount, error)

MountStats retrieves statistics and configuration for mount points in a process's namespace.

func (Proc) NewIO

func (p Proc) NewIO() (ProcIO, error)

NewIO creates a new ProcIO instance from a given Proc instance.

func (Proc) NewLimits

func (p Proc) NewLimits() (ProcLimits, error)

NewLimits returns the current soft limits of the process.

func (Proc) NewStat

func (p Proc) NewStat() (ProcStat, error)

NewStat returns the current status information of the process.

type ProcIO

ProcIO models the content of /proc/<pid>/io.

type ProcIO struct {
    // Chars read.
    RChar uint64
    // Chars written.
    WChar uint64
    // Read syscalls.
    SyscR uint64
    // Write syscalls.
    SyscW uint64
    // Bytes read.
    ReadBytes uint64
    // Bytes written.
    WriteBytes uint64
    // Bytes written, but taking into account truncation. See
    // Documentation/filesystems/proc.txt in the kernel sources for
    // detailed explanation.
    CancelledWriteBytes int64
}

type ProcLimits

ProcLimits represents the soft limits for each of the process's resource limits. For more information see getrlimit(2): http://man7.org/linux/man-pages/man2/getrlimit.2.html.

type ProcLimits struct {
    // CPU time limit in seconds.
    CPUTime int
    // Maximum size of files that the process may create.
    FileSize int
    // Maximum size of the process's data segment (initialized data,
    // uninitialized data, and heap).
    DataSize int
    // Maximum size of the process stack in bytes.
    StackSize int
    // Maximum size of a core file.
    CoreFileSize int
    // Limit of the process's resident set in pages.
    ResidentSet int
    // Maximum number of processes that can be created for the real user ID of
    // the calling process.
    Processes int
    // Value one greater than the maximum file descriptor number that can be
    // opened by this process.
    OpenFiles int
    // Maximum number of bytes of memory that may be locked into RAM.
    LockedMemory int
    // Maximum size of the process's virtual memory address space in bytes.
    AddressSpace int
    // Limit on the combined number of flock(2) locks and fcntl(2) leases that
    // this process may establish.
    FileLocks int
    // Limit of signals that may be queued for the real user ID of the calling
    // process.
    PendingSignals int
    // Limit on the number of bytes that can be allocated for POSIX message
    // queues for the real user ID of the calling process.
    MsqqueueSize int
    // Limit of the nice priority set using setpriority(2) or nice(2).
    NicePriority int
    // Limit of the real-time priority set using sched_setscheduler(2) or
    // sched_setparam(2).
    RealtimePriority int
    // Limit (in microseconds) on the amount of CPU time that a process
    // scheduled under a real-time scheduling policy may consume without making
    // a blocking system call.
    RealtimeTimeout int
}

type ProcStat

ProcStat provides status information about the process, read from /proc/[pid]/stat.

type ProcStat struct {
    // The process ID.
    PID int
    // The filename of the executable.
    Comm string
    // The process state.
    State string
    // The PID of the parent of this process.
    PPID int
    // The process group ID of the process.
    PGRP int
    // The session ID of the process.
    Session int
    // The controlling terminal of the process.
    TTY int
    // The ID of the foreground process group of the controlling terminal of
    // the process.
    TPGID int
    // The kernel flags word of the process.
    Flags uint
    // The number of minor faults the process has made which have not required
    // loading a memory page from disk.
    MinFlt uint
    // The number of minor faults that the process's waited-for children have
    // made.
    CMinFlt uint
    // The number of major faults the process has made which have required
    // loading a memory page from disk.
    MajFlt uint
    // The number of major faults that the process's waited-for children have
    // made.
    CMajFlt uint
    // Amount of time that this process has been scheduled in user mode,
    // measured in clock ticks.
    UTime uint
    // Amount of time that this process has been scheduled in kernel mode,
    // measured in clock ticks.
    STime uint
    // Amount of time that this process's waited-for children have been
    // scheduled in user mode, measured in clock ticks.
    CUTime uint
    // Amount of time that this process's waited-for children have been
    // scheduled in kernel mode, measured in clock ticks.
    CSTime uint
    // For processes running a real-time scheduling policy, this is the negated
    // scheduling priority, minus one.
    Priority int
    // The nice value, a value in the range 19 (low priority) to -20 (high
    // priority).
    Nice int
    // Number of threads in this process.
    NumThreads int
    // The time the process started after system boot, the value is expressed
    // in clock ticks.
    Starttime uint64
    // Virtual memory size in bytes.
    VSize int
    // Resident set size in pages.
    RSS int
    // contains filtered or unexported fields
}

func (ProcStat) CPUTime

func (s ProcStat) CPUTime() float64

CPUTime returns the total CPU user and system time in seconds.

func (ProcStat) ResidentMemory

func (s ProcStat) ResidentMemory() int

ResidentMemory returns the resident memory size in bytes.

func (ProcStat) StartTime

func (s ProcStat) StartTime() (float64, error)

StartTime returns the unix timestamp of the process in seconds.

func (ProcStat) VirtualMemory

func (s ProcStat) VirtualMemory() int

VirtualMemory returns the virtual memory size in bytes.

type Procs

Procs represents a list of Proc structs.

type Procs []Proc

func AllProcs

func AllProcs() (Procs, error)

AllProcs returns a list of all currently available processes under /proc.

func (Procs) Len

func (p Procs) Len() int

func (Procs) Less

func (p Procs) Less(i, j int) bool

func (Procs) Swap

func (p Procs) Swap(i, j int)

type SoftIRQStat

SoftIRQStat represent the softirq statistics as exported in the procfs stat file. A nice introduction can be found at https://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-9.html It is possible to get per-cpu stats by reading /proc/softirqs

type SoftIRQStat struct {
    Hi          uint64
    Timer       uint64
    NetTx       uint64
    NetRx       uint64
    Block       uint64
    BlockIoPoll uint64
    Tasklet     uint64
    Sched       uint64
    Hrtimer     uint64
    Rcu         uint64
}

type Stat

Stat represents kernel/system statistics.

type Stat struct {
    // Boot time in seconds since the Epoch.
    BootTime uint64
    // Summed up cpu statistics.
    CPUTotal CPUStat
    // Per-CPU statistics.
    CPU []CPUStat
    // Number of times interrupts were handled, which contains numbered and unnumbered IRQs.
    IRQTotal uint64
    // Number of times a numbered IRQ was triggered.
    IRQ []uint64
    // Number of times a context switch happened.
    ContextSwitches uint64
    // Number of times a process was created.
    ProcessCreated uint64
    // Number of processes currently running.
    ProcessesRunning uint64
    // Number of processes currently blocked (waiting for IO).
    ProcessesBlocked uint64
    // Number of times a softirq was scheduled.
    SoftIRQTotal uint64
    // Detailed softirq statistics.
    SoftIRQ SoftIRQStat
}

func NewStat

func NewStat() (Stat, error)

NewStat returns kernel/system statistics read from /proc/stat.

type XfrmStat

XfrmStat models the contents of /proc/net/xfrm_stat.

type XfrmStat struct {
    // All errors which are not matched by other
    XfrmInError int
    // No buffer is left
    XfrmInBufferError int
    // Header Error
    XfrmInHdrError int
    // No state found
    // i.e. either inbound SPI, address, or IPSEC protocol at SA is wrong
    XfrmInNoStates int
    // Transformation protocol specific error
    // e.g. SA Key is wrong
    XfrmInStateProtoError int
    // Transformation mode specific error
    XfrmInStateModeError int
    // Sequence error
    // e.g. sequence number is out of window
    XfrmInStateSeqError int
    // State is expired
    XfrmInStateExpired int
    // State has mismatch option
    // e.g. UDP encapsulation type is mismatched
    XfrmInStateMismatch int
    // State is invalid
    XfrmInStateInvalid int
    // No matching template for states
    // e.g. Inbound SAs are correct but SP rule is wrong
    XfrmInTmplMismatch int
    // No policy is found for states
    // e.g. Inbound SAs are correct but no SP is found
    XfrmInNoPols int
    // Policy discards
    XfrmInPolBlock int
    // Policy error
    XfrmInPolError int
    // All errors which are not matched by others
    XfrmOutError int
    // Bundle generation error
    XfrmOutBundleGenError int
    // Bundle check error
    XfrmOutBundleCheckError int
    // No state was found
    XfrmOutNoStates int
    // Transformation protocol specific error
    XfrmOutStateProtoError int
    // Transportation mode specific error
    XfrmOutStateModeError int
    // Sequence error
    // i.e sequence number overflow
    XfrmOutStateSeqError int
    // State is expired
    XfrmOutStateExpired int
    // Policy discads
    XfrmOutPolBlock int
    // Policy is dead
    XfrmOutPolDead int
    // Policy Error
    XfrmOutPolError     int
    XfrmFwdHdrError     int
    XfrmOutStateInvalid int
    XfrmAcquireError    int
}

func NewXfrmStat

func NewXfrmStat() (XfrmStat, error)

NewXfrmStat reads the xfrm_stat statistics.

Subdirectories

Name Synopsis
..
bcache Package bcache provides access to statistics exposed by the bcache (Linux block cache).
sysfs Package sysfs provides functions to retrieve system and kernel metrics from the pseudo-filesystem sys.
xfs Package xfs provides access to statistics exposed by the XFS filesystem.