backup: rework read concurrency

pull/102/head
Michael Eischer 2 months ago
parent 4a501d7118
commit 2e606ca70b

@ -1,5 +1,6 @@
Enhancement: Make backup file read concurrency configurable
In order to tune restic for special situations we need to be able to configure `backup --file-read-concurrency`.
The `backup` command now supports a `--read-concurrency` flag to allowing
tuning restic for very fast storage like NVME disks.
https://github.com/restic/restic/pull/2750

@ -101,7 +101,7 @@ type BackupOptions struct {
IgnoreCtime bool
UseFsSnapshot bool
DryRun bool
FileReadConcurrency uint
ReadConcurrency uint
}
var backupOptions BackupOptions
@ -110,12 +110,6 @@ var backupOptions BackupOptions
var ErrInvalidSourceData = errors.New("at least one source file could not be read")
func init() {
//set FileReadConcurrency to 2 if not set in env
fileReadConcurrency, err := strconv.ParseUint(os.Getenv("RESTIC_FILE_READ_CONCURRENCY"), 10, 32)
if err != nil || fileReadConcurrency < 1 {
fileReadConcurrency = 2
}
cmdRoot.AddCommand(cmdBackup)
f := cmdBackup.Flags()
@ -132,10 +126,10 @@ func init() {
f.BoolVar(&backupOptions.Stdin, "stdin", false, "read backup from stdin")
f.StringVar(&backupOptions.StdinFilename, "stdin-filename", "stdin", "`filename` to use when reading from stdin")
f.Var(&backupOptions.Tags, "tag", "add `tags` for the new snapshot in the format `tag[,tag,...]` (can be specified multiple times)")
f.UintVar(&backupOptions.FileReadConcurrency, "file-read-concurrency", uint(fileReadConcurrency), "set concurrency on file reads. (default: $RESTIC_FILE_READ_CONCURRENCY or 2)")
f.UintVar(&backupOptions.ReadConcurrency, "read-concurrency", 0, "read `n` file concurrently. (default: $RESTIC_READ_CONCURRENCY or 2)")
f.StringVarP(&backupOptions.Host, "host", "H", "", "set the `hostname` for the snapshot manually. To prevent an expensive rescan use the \"parent\" flag")
f.StringVar(&backupOptions.Host, "hostname", "", "set the `hostname` for the snapshot manually")
err = f.MarkDeprecated("hostname", "use --host")
err := f.MarkDeprecated("hostname", "use --host")
if err != nil {
// MarkDeprecated only returns an error when the flag could not be found
panic(err)
@ -152,6 +146,9 @@ func init() {
f.BoolVar(&backupOptions.UseFsSnapshot, "use-fs-snapshot", false, "use filesystem snapshot where possible (currently only Windows VSS)")
}
// parse read concurrency from env, on error the default value will be used
readConcurrency, _ := strconv.ParseUint(os.Getenv("RESTIC_READ_CONCURRENCY"), 10, 32)
backupOptions.ReadConcurrency = uint(readConcurrency)
}
// filterExisting returns a slice of all existing items, or an error if no
@ -292,10 +289,6 @@ func (opts BackupOptions) Check(gopts GlobalOptions, args []string) error {
}
}
if backupOptions.FileReadConcurrency == 0 {
return errors.Fatal("--file-read-concurrency must be a positive, nonzero integer")
}
return nil
}
@ -697,7 +690,7 @@ func runBackup(opts BackupOptions, gopts GlobalOptions, term *termstatus.Termina
}
wg.Go(func() error { return sc.Scan(cancelCtx, targets) })
arch := archiver.New(repo, targetFS, archiver.Options{FileReadConcurrency: backupOptions.FileReadConcurrency})
arch := archiver.New(repo, targetFS, archiver.Options{ReadConcurrency: backupOptions.ReadConcurrency})
arch.SelectByName = selectByNameFilter
arch.Select = selectFilter
arch.WithAtime = opts.WithAtime

@ -555,6 +555,7 @@ environment variables. The following lists these environment variables:
RESTIC_COMPRESSION Compression mode (only available for repository format version 2)
RESTIC_PROGRESS_FPS Frames per second by which the progress bar is updated
RESTIC_PACK_SIZE Target size for pack files
RESTIC_READ_CONCURRENCY Concurrency for file reads
TMPDIR Location for temporary files

@ -54,11 +54,11 @@ variable ``RESTIC_COMPRESSION``.
File Read Concurrency
=====================
In some instances, such as backing up traditional spinning disks, reducing the file read
concurrency is desired. This will help reduce the amount of time spent seeking around
the disk and can increase the overall performance of the backup operation. You can specify
the concurrency of file reads with the ``RESTIC_FILE_READ_CONCURRENCY`` environment variable
or the ``--file-read-concurrency`` flag for the ``backup`` subcommand.
When backing up fast storage like NVME disks, it can be beneficial to increase the read
concurrency. This can increase the overall performance of the backup operation by reading
more files in parallel. You can specify the concurrency of file reads with the
``RESTIC_READ_CONCURRENCY`` environment variable or the ``--read-concurrency`` flag for
the ``backup`` command.
Pack Size

@ -103,7 +103,6 @@ command:
--files-from file read the files to backup from file (can be combined with file args; can be specified multiple times)
--files-from-raw file read the files to backup from file (can be combined with file args; can be specified multiple times)
--files-from-verbatim file read the files to backup from file (can be combined with file args; can be specified multiple times)
--file-read-concurrency uint set concurrency on file reads. (default: $RESTIC_FILE_READ_CONCURRENCY or 2)
-f, --force force re-reading the target files/directories (overrides the "parent" flag)
-h, --help help for backup
-H, --host hostname set the hostname for the snapshot manually. To prevent an expensive rescan use the "parent" flag
@ -113,6 +112,7 @@ command:
--ignore-inode ignore inode number changes when checking for modified files
-x, --one-file-system exclude other file systems, don't cross filesystem boundaries and subvolumes
--parent snapshot use this parent snapshot (default: last snapshot in the repository that has the same target files/directories, and is not newer than the snapshot time)
--read-concurrency n read n file concurrently. (default: $RESTIC_READ_CONCURRENCY or 2)
--stdin read backup from stdin
--stdin-filename filename filename to use when reading from stdin (default "stdin")
--tag tags add tags for the new snapshot in the format `tag[,tag,...]` (can be specified multiple times) (default [])

@ -95,10 +95,10 @@ const (
// Options is used to configure the archiver.
type Options struct {
// FileReadConcurrency sets how many files are read in concurrently. If
// ReadConcurrency sets how many files are read in concurrently. If
// it's set to zero, at most two files are read in concurrently (which
// turned out to be a good default for most situations).
FileReadConcurrency uint
ReadConcurrency uint
// SaveBlobConcurrency sets how many blobs are hashed and saved
// concurrently. If it's set to zero, the default is the number of CPUs
@ -113,11 +113,11 @@ type Options struct {
// ApplyDefaults returns a copy of o with the default options set for all unset
// fields.
func (o Options) ApplyDefaults() Options {
if o.FileReadConcurrency == 0 {
if o.ReadConcurrency == 0 {
// two is a sweet spot for almost all situations. We've done some
// experiments documented here:
// https://github.com/borgbackup/borg/issues/3500
o.FileReadConcurrency = 2
o.ReadConcurrency = 2
}
if o.SaveBlobConcurrency == 0 {
@ -132,7 +132,7 @@ func (o Options) ApplyDefaults() Options {
// Also allow waiting for FileReadConcurrency files, this is the maximum of FutureFiles
// which currently can be in progress. The main backup loop blocks when trying to queue
// more files to read.
o.SaveTreeConcurrency = uint(runtime.GOMAXPROCS(0)) + o.FileReadConcurrency
o.SaveTreeConcurrency = uint(runtime.GOMAXPROCS(0)) + o.ReadConcurrency
}
return o
@ -782,7 +782,7 @@ func (arch *Archiver) runWorkers(ctx context.Context, wg *errgroup.Group) {
arch.fileSaver = NewFileSaver(ctx, wg,
arch.blobSaver.Save,
arch.Repo.Config().ChunkerPolynomial,
arch.Options.FileReadConcurrency, arch.Options.SaveBlobConcurrency)
arch.Options.ReadConcurrency, arch.Options.SaveBlobConcurrency)
arch.fileSaver.CompleteBlob = arch.CompleteBlob
arch.fileSaver.NodeFromFileInfo = arch.nodeFromFileInfo

@ -2040,7 +2040,7 @@ func TestArchiverAbortEarlyOnError(t *testing.T) {
// at most two files may be queued
arch := New(testRepo, testFS, Options{
FileReadConcurrency: 2,
ReadConcurrency: 2,
})
_, _, err := arch.Snapshot(ctx, []string{"."}, SnapshotOptions{Time: time.Now()})

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