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// Copyright 2018 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package blockdevice
import (
"bufio"
"errors"
"fmt"
"io"
"os"
"strings"
"github.com/prometheus/procfs"
"github.com/prometheus/procfs/internal/fs"
"github.com/prometheus/procfs/internal/util"
)
// Info contains identifying information for a block device such as a disk drive.
type Info struct {
MajorNumber uint32
MinorNumber uint32
DeviceName string
}
// IOStats models the iostats data described in the kernel documentation.
// - https://www.kernel.org/doc/Documentation/iostats.txt,
// - https://www.kernel.org/doc/Documentation/block/stat.txt
// - https://www.kernel.org/doc/Documentation/ABI/testing/procfs-diskstats
type IOStats struct {
// ReadIOs is the number of reads completed successfully.
ReadIOs uint64
// ReadMerges is the number of reads merged. Reads and writes
// which are adjacent to each other may be merged for efficiency.
ReadMerges uint64
// ReadSectors is the total number of sectors read successfully.
ReadSectors uint64
// ReadTicks is the total number of milliseconds spent by all reads.
ReadTicks uint64
// WriteIOs is the total number of writes completed successfully.
WriteIOs uint64
// WriteMerges is the number of reads merged.
WriteMerges uint64
// WriteSectors is the total number of sectors written successfully.
WriteSectors uint64
// WriteTicks is the total number of milliseconds spent by all writes.
WriteTicks uint64
// IOsInProgress is number of I/Os currently in progress.
IOsInProgress uint64
// IOsTotalTicks is the number of milliseconds spent doing I/Os.
// This field increases so long as IosInProgress is nonzero.
IOsTotalTicks uint64
// WeightedIOTicks is the weighted number of milliseconds spent doing I/Os.
// This can also be used to estimate average queue wait time for requests.
WeightedIOTicks uint64
// DiscardIOs is the total number of discards completed successfully.
DiscardIOs uint64
// DiscardMerges is the number of discards merged.
DiscardMerges uint64
// DiscardSectors is the total number of sectors discarded successfully.
DiscardSectors uint64
// DiscardTicks is the total number of milliseconds spent by all discards.
DiscardTicks uint64
// FlushRequestsCompleted is the total number of flush request completed successfully.
FlushRequestsCompleted uint64
// TimeSpentFlushing is the total number of milliseconds spent flushing.
TimeSpentFlushing uint64
}
// Diskstats combines the device Info and IOStats.
type Diskstats struct {
Info
IOStats
// IoStatsCount contains the number of io stats read. For kernel versions 5.5+,
// there should be 20 fields read. For kernel versions 4.18+,
// there should be 18 fields read. For earlier kernel versions this
// will be 14 because the discard values are not available.
IoStatsCount int
}
// BlockQueueStats models the queue files that are located in the sysfs tree for each block device
// and described in the kernel documentation:
// https://www.kernel.org/doc/Documentation/block/queue-sysfs.txt
// https://www.kernel.org/doc/html/latest/block/queue-sysfs.html
type BlockQueueStats struct {
// AddRandom is the status of a disk entropy (1 is on, 0 is off).
AddRandom uint64
// Dax indicates whether the device supports Direct Access (DAX) (1 is on, 0 is off).
DAX uint64
// DiscardGranularity is the size of internal allocation of the device in bytes, 0 means device
// does not support the discard functionality.
DiscardGranularity uint64
// DiscardMaxHWBytes is the hardware maximum number of bytes that can be discarded in a single operation,
// 0 means device does not support the discard functionality.
DiscardMaxHWBytes uint64
// DiscardMaxBytes is the software maximum number of bytes that can be discarded in a single operation.
DiscardMaxBytes uint64
// HWSectorSize is the sector size of the device, in bytes.
HWSectorSize uint64
// IOPoll indicates if polling is enabled (1 is on, 0 is off).
IOPoll uint64
// IOPollDelay indicates how polling will be performed, -1 for classic polling, 0 for hybrid polling,
// with greater than 0 the kernel will put process issuing IO to sleep for this amount of time in
// microseconds before entering classic polling.
IOPollDelay int64
// IOTimeout is the request timeout in milliseconds.
IOTimeout uint64
// IOStats indicates if iostats accounting is used for the disk (1 is on, 0 is off).
IOStats uint64
// LogicalBlockSize is the logical block size of the device, in bytes.
LogicalBlockSize uint64
// MaxHWSectorsKB is the maximum number of kilobytes supported in a single data transfer.
MaxHWSectorsKB uint64
// MaxIntegritySegments is the max limit of integrity segments as set by block layer which a hardware controller
// can handle.
MaxIntegritySegments uint64
// MaxSectorsKB is the maximum number of kilobytes that the block layer will allow for a filesystem request.
MaxSectorsKB uint64
// MaxSegments is the number of segments on the device.
MaxSegments uint64
// MaxSegmentsSize is the maximum segment size of the device.
MaxSegmentSize uint64
// MinimumIOSize is the smallest preferred IO size reported by the device.
MinimumIOSize uint64
// NoMerges shows the lookup logic involved with IO merging requests in the block layer. 0 all merges are
// enabled, 1 only simple one hit merges are tried, 2 no merge algorithms will be tried.
NoMerges uint64
// NRRequests is the number of how many requests may be allocated in the block layer for read or write requests.
NRRequests uint64
// OptimalIOSize is the optimal IO size reported by the device.
OptimalIOSize uint64
// PhysicalBlockSize is the physical block size of device, in bytes.
PhysicalBlockSize uint64
// ReadAHeadKB is the maximum number of kilobytes to read-ahead for filesystems on this block device.
ReadAHeadKB uint64
// Rotational indicates if the device is of rotational type or non-rotational type.
Rotational uint64
// RQAffinity indicates affinity policy of device, if 1 the block layer will migrate request completions to the
// cpu “group” that originally submitted the request, if 2 forces the completion to run on the requesting cpu.
RQAffinity uint64
// SchedulerList contains list of available schedulers for this block device.
SchedulerList []string
// SchedulerCurrent is the current scheduler for this block device.
SchedulerCurrent string
// WriteCache shows the type of cache for block device, "write back" or "write through".
WriteCache string
// WriteSameMaxBytes is the number of bytes the device can write in a single write-same command.
// A value of ‘0’ means write-same is not supported by this device.
WriteSameMaxBytes uint64
// WBTLatUSec is the target minimum read latency, 0 means feature is disables.
WBTLatUSec int64
// ThrottleSampleTime is the time window that blk-throttle samples data, in millisecond. Optional
// exists only if CONFIG_BLK_DEV_THROTTLING_LOW is enabled.
ThrottleSampleTime *uint64
// Zoned indicates if the device is a zoned block device and the zone model of the device if it is indeed zoned.
// Possible values are: none, host-aware, host-managed for zoned block devices.
Zoned string
// NRZones indicates the total number of zones of the device, always zero for regular block devices.
NRZones uint64
// ChunksSectors for RAID is the size in 512B sectors of the RAID volume stripe segment,
// for zoned host device is the size in 512B sectors.
ChunkSectors uint64
// FUA indicates whether the device supports Force Unit Access for write requests.
FUA uint64
// MaxDiscardSegments is the maximum number of DMA entries in a discard request.
MaxDiscardSegments uint64
// WriteZeroesMaxBytes the maximum number of bytes that can be zeroed at once.
// The value 0 means that REQ_OP_WRITE_ZEROES is not supported.
WriteZeroesMaxBytes uint64
}
type IODeviceStats struct {
IODoneCount uint64
IOErrCount uint64
}
// DeviceMapperInfo models the devicemapper files that are located in the sysfs tree for each block device
// and described in the kernel documentation:
// https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-block-dm
type DeviceMapperInfo struct {
// Name is the string containing mapped device name.
Name string
// RqBasedSeqIOMergeDeadline determines how long (in microseconds) a request that is a reasonable merge
// candidate can be queued on the request queue.
RqBasedSeqIOMergeDeadline uint64
// Suspended indicates if the device is suspended (1 is on, 0 is off).
Suspended uint64
// UseBlkMQ indicates if the device is using the request-based blk-mq I/O path mode (1 is on, 0 is off).
UseBlkMQ uint64
// UUID is the DM-UUID string or empty string if DM-UUID is not set.
UUID string
}
// UnderlyingDevices models the list of devices that this device is built from.
type UnderlyingDeviceInfo struct {
// DeviceNames is the list of devices names
DeviceNames []string
}
const (
procDiskstatsPath = "diskstats"
procDiskstatsFormat = "%d %d %s %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d"
sysBlockPath = "block"
sysBlockStatFormat = "%d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d"
sysBlockQueue = "queue"
sysBlockDM = "dm"
sysUnderlyingDev = "slaves"
sysBlockSize = "size"
sysDevicePath = "device"
)
// FS represents the pseudo-filesystems proc and sys, which provides an
// interface to kernel data structures.
type FS struct {
proc *fs.FS
sys *fs.FS
}
// NewDefaultFS returns a new blockdevice fs using the default mountPoints for proc and sys.
// It will error if either of these mount points can't be read.
func NewDefaultFS() (FS, error) {
return NewFS(fs.DefaultProcMountPoint, fs.DefaultSysMountPoint)
}
// NewFS returns a new blockdevice fs using the given mountPoints for proc and sys.
// It will error if either of these mount points can't be read.
func NewFS(procMountPoint string, sysMountPoint string) (FS, error) {
if strings.TrimSpace(procMountPoint) == "" {
procMountPoint = fs.DefaultProcMountPoint
}
procfs, err := fs.NewFS(procMountPoint)
if err != nil {
return FS{}, err
}
if strings.TrimSpace(sysMountPoint) == "" {
sysMountPoint = fs.DefaultSysMountPoint
}
sysfs, err := fs.NewFS(sysMountPoint)
if err != nil {
return FS{}, err
}
return FS{&procfs, &sysfs}, nil
}
// ProcDiskstats reads the diskstats file and returns
// an array of Diskstats (one per line/device).
func (fs FS) ProcDiskstats() ([]Diskstats, error) {
file, err := os.Open(fs.proc.Path(procDiskstatsPath))
if err != nil {
return nil, err
}
defer file.Close()
return parseProcDiskstats(file)
}
func parseProcDiskstats(r io.Reader) ([]Diskstats, error) {
var (
diskstats []Diskstats
scanner = bufio.NewScanner(r)
err error
)
for scanner.Scan() {
d := &Diskstats{}
d.IoStatsCount, err = fmt.Sscanf(scanner.Text(), procDiskstatsFormat,
&d.MajorNumber,
&d.MinorNumber,
&d.DeviceName,
&d.ReadIOs,
&d.ReadMerges,
&d.ReadSectors,
&d.ReadTicks,
&d.WriteIOs,
&d.WriteMerges,
&d.WriteSectors,
&d.WriteTicks,
&d.IOsInProgress,
&d.IOsTotalTicks,
&d.WeightedIOTicks,
&d.DiscardIOs,
&d.DiscardMerges,
&d.DiscardSectors,
&d.DiscardTicks,
&d.FlushRequestsCompleted,
&d.TimeSpentFlushing,
)
// The io.EOF error can be safely ignored because it just means we read fewer than
// the full 20 fields.
if err != nil && !errors.Is(err, io.EOF) {
return diskstats, err
}
if d.IoStatsCount >= 14 {
diskstats = append(diskstats, *d)
}
}
return diskstats, scanner.Err()
}
// SysBlockDevices lists the device names from /sys/block/<dev>.
func (fs FS) SysBlockDevices() ([]string, error) {
deviceDirs, err := os.ReadDir(fs.sys.Path(sysBlockPath))
if err != nil {
return nil, err
}
devices := []string{}
for _, deviceDir := range deviceDirs {
devices = append(devices, deviceDir.Name())
}
return devices, nil
}
// SysBlockDeviceStat returns stats for the block device read from /sys/block/<device>/stat.
// The number of stats read will be 15 if the discard stats are available (kernel 4.18+)
// and 11 if they are not available.
func (fs FS) SysBlockDeviceStat(device string) (IOStats, int, error) {
bytes, err := os.ReadFile(fs.sys.Path(sysBlockPath, device, "stat"))
if err != nil {
return IOStats{}, 0, err
}
return parseSysBlockDeviceStat(bytes)
}
func parseSysBlockDeviceStat(data []byte) (IOStats, int, error) {
stat := IOStats{}
count, err := fmt.Sscanf(strings.TrimSpace(string(data)), sysBlockStatFormat,
&stat.ReadIOs,
&stat.ReadMerges,
&stat.ReadSectors,
&stat.ReadTicks,
&stat.WriteIOs,
&stat.WriteMerges,
&stat.WriteSectors,
&stat.WriteTicks,
&stat.IOsInProgress,
&stat.IOsTotalTicks,
&stat.WeightedIOTicks,
&stat.DiscardIOs,
&stat.DiscardMerges,
&stat.DiscardSectors,
&stat.DiscardTicks,
&stat.FlushRequestsCompleted,
&stat.TimeSpentFlushing,
)
// An io.EOF error is ignored because it just means we read fewer than the full 15 fields.
if errors.Is(err, io.EOF) {
return stat, count, nil
}
return stat, count, err
}
// SysBlockDeviceQueueStats returns stats for /sys/block/xxx/queue where xxx is a device name.
func (fs FS) SysBlockDeviceQueueStats(device string) (BlockQueueStats, error) {
stat := BlockQueueStats{}
// Files with uint64 fields
for file, p := range map[string]*uint64{
"add_random": &stat.AddRandom,
"dax": &stat.DAX,
"discard_granularity": &stat.DiscardGranularity,
"discard_max_hw_bytes": &stat.DiscardMaxHWBytes,
"discard_max_bytes": &stat.DiscardMaxBytes,
"hw_sector_size": &stat.HWSectorSize,
"io_poll": &stat.IOPoll,
"io_timeout": &stat.IOTimeout,
"iostats": &stat.IOStats,
"logical_block_size": &stat.LogicalBlockSize,
"max_hw_sectors_kb": &stat.MaxHWSectorsKB,
"max_integrity_segments": &stat.MaxIntegritySegments,
"max_sectors_kb": &stat.MaxSectorsKB,
"max_segments": &stat.MaxSegments,
"max_segment_size": &stat.MaxSegmentSize,
"minimum_io_size": &stat.MinimumIOSize,
"nomerges": &stat.NoMerges,
"nr_requests": &stat.NRRequests,
"optimal_io_size": &stat.OptimalIOSize,
"physical_block_size": &stat.PhysicalBlockSize,
"read_ahead_kb": &stat.ReadAHeadKB,
"rotational": &stat.Rotational,
"rq_affinity": &stat.RQAffinity,
"write_same_max_bytes": &stat.WriteSameMaxBytes,
"nr_zones": &stat.NRZones,
"chunk_sectors": &stat.ChunkSectors,
"fua": &stat.FUA,
"max_discard_segments": &stat.MaxDiscardSegments,
"write_zeroes_max_bytes": &stat.WriteZeroesMaxBytes,
} {
val, err := util.ReadUintFromFile(fs.sys.Path(sysBlockPath, device, sysBlockQueue, file))
if err != nil {
return BlockQueueStats{}, err
}
*p = val
}
// Files with int64 fields
for file, p := range map[string]*int64{
"io_poll_delay": &stat.IOPollDelay,
"wbt_lat_usec": &stat.WBTLatUSec,
} {
val, err := util.ReadIntFromFile(fs.sys.Path(sysBlockPath, device, sysBlockQueue, file))
if err != nil {
return BlockQueueStats{}, err
}
*p = val
}
// Files with string fields
for file, p := range map[string]*string{
"write_cache": &stat.WriteCache,
"zoned": &stat.Zoned,
} {
val, err := util.SysReadFile(fs.sys.Path(sysBlockPath, device, sysBlockQueue, file))
if err != nil {
return BlockQueueStats{}, err
}
*p = val
}
scheduler, err := util.SysReadFile(fs.sys.Path(sysBlockPath, device, sysBlockQueue, "scheduler"))
if err != nil {
return BlockQueueStats{}, err
}
var schedulers []string
xs := strings.Split(scheduler, " ")
for _, s := range xs {
if strings.HasPrefix(s, "[") && strings.HasSuffix(s, "]") {
s = s[1 : len(s)-1]
stat.SchedulerCurrent = s
}
schedulers = append(schedulers, s)
}
stat.SchedulerList = schedulers
// optional
throttleSampleTime, err := util.ReadUintFromFile(fs.sys.Path(sysBlockPath, device, sysBlockQueue, "throttle_sample_time"))
if err == nil {
stat.ThrottleSampleTime = &throttleSampleTime
}
return stat, nil
}
func (fs FS) SysBlockDeviceMapperInfo(device string) (DeviceMapperInfo, error) {
info := DeviceMapperInfo{}
// Files with uint64 fields
for file, p := range map[string]*uint64{
"rq_based_seq_io_merge_deadline": &info.RqBasedSeqIOMergeDeadline,
"suspended": &info.Suspended,
"use_blk_mq": &info.UseBlkMQ,
} {
val, err := util.ReadUintFromFile(fs.sys.Path(sysBlockPath, device, sysBlockDM, file))
if err != nil {
return DeviceMapperInfo{}, err
}
*p = val
}
// Files with string fields
for file, p := range map[string]*string{
"name": &info.Name,
"uuid": &info.UUID,
} {
val, err := util.SysReadFile(fs.sys.Path(sysBlockPath, device, sysBlockDM, file))
if err != nil {
return DeviceMapperInfo{}, err
}
*p = val
}
return info, nil
}
func (fs FS) SysBlockDeviceUnderlyingDevices(device string) (UnderlyingDeviceInfo, error) {
underlyingDir, err := os.Open(fs.sys.Path(sysBlockPath, device, sysUnderlyingDev))
if err != nil {
return UnderlyingDeviceInfo{}, err
}
underlying, err := underlyingDir.Readdirnames(0)
if err != nil {
return UnderlyingDeviceInfo{}, err
}
return UnderlyingDeviceInfo{DeviceNames: underlying}, nil
}
// SysBlockDeviceSize returns the size of the block device from /sys/block/<device>/size
// in bytes by multiplying the value by the Linux sector length of 512.
func (fs FS) SysBlockDeviceSize(device string) (uint64, error) {
size, err := util.ReadUintFromFile(fs.sys.Path(sysBlockPath, device, sysBlockSize))
if err != nil {
return 0, err
}
return procfs.SectorSize * size, nil
}
// SysBlockDeviceIO returns stats for the block device io counters
// IO done count: /sys/block/<disk>/device/iodone_cnt
// IO error count: /sys/block/<disk>/device/ioerr_cnt.
func (fs FS) SysBlockDeviceIOStat(device string) (IODeviceStats, error) {
var (
ioDeviceStats IODeviceStats
err error
)
for file, p := range map[string]*uint64{
"iodone_cnt": &ioDeviceStats.IODoneCount,
"ioerr_cnt": &ioDeviceStats.IOErrCount,
} {
var val uint64
val, err = util.ReadHexFromFile(fs.sys.Path(sysBlockPath, device, sysDevicePath, file))
if err != nil {
return IODeviceStats{}, err
}
*p = val
}
return ioDeviceStats, nil
}
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