thaloco/banger
1
Fork 0
Code Pull requests Releases Packages Activity Actions

Speed up VM create with work seeds

Browse source 
Beat VM create wall time without changing VM semantics.

Generate a work-seed ext4 sidecar during image builds and rootfs rebuilds, then clone and resize that seed for each new VM instead of rebuilding /root from scratch. Plumb the new seed artifact through config, runtime metadata, store state, runtime-bundle defaults, doctor checks, and default-image reconciliation so older images still fall back cleanly.

Add a daemon TAP pool to keep idle bridge-attached devices warm, expose stage timing in lifecycle logs, add a create/SSH benchmark script plus Make target, and teach verify.sh that tap-pool-* devices are reusable capacity rather than cleanup leaks.

Validated with go test ./..., make build, ./verify.sh, and make bench-create ARGS="--runs 2".
This commit is contained in:
Thales Maciel 2026-03-18 21:22:12 -03:00
parent a14a80fd6b
commit c8d9a122f9
No known key found for this signature in database
GPG key ID: 33112E6833C34679
24 changed files with 695 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

54
internal/daemon/vm.go
View file

@ -188,8 +188,8 @@ func (d *Daemon) startVMLocked(ctx context.Context, vm model.VMRecord, image mod
shortID := system.ShortID(vm.ID)
apiSock := filepath.Join(d.layout.RuntimeDir, "fc-"+shortID+".sock")
tap := "tap-fc-" + shortID
dmName := "fc-rootfs-" + shortID
tapName := "tap-fc-" + shortID
if strings.TrimSpace(vm.Runtime.VSockPath) == "" {
vm.Runtime.VSockPath = defaultVSockPath(d.layout.RuntimeDir, vm.ID)
}
@ -221,7 +221,6 @@ func (d *Daemon) startVMLocked(ctx context.Context, vm model.VMRecord, image mod
vm.Runtime.DMName = handles.DMName
vm.Runtime.DMDev = handles.DMDev
vm.Runtime.APISockPath = apiSock
vm.Runtime.TapDevice = tap
vm.Runtime.State = model.VMStateRunning
vm.State = model.VMStateRunning
vm.Runtime.LastError = ""
@ -247,10 +246,12 @@ func (d *Daemon) startVMLocked(ctx context.Context, vm model.VMRecord, image mod
if err := d.prepareCapabilityHosts(ctx, &vm, image); err != nil {
return cleanupOnErr(err)
}
op.stage("tap", "tap_device", tap)
if err := d.createTap(ctx, tap); err != nil {
op.stage("tap")
tap, err := d.acquireTap(ctx, tapName)
if err != nil {
return cleanupOnErr(err)
}
vm.Runtime.TapDevice = tap
op.stage("metrics_file", "metrics_path", vm.Runtime.MetricsPath)
if err := os.WriteFile(vm.Runtime.MetricsPath, nil, 0o644); err != nil {
return cleanupOnErr(err)
@ -766,10 +767,28 @@ func (d *Daemon) patchRootOverlay(ctx context.Context, vm model.VMRecord, image
return nil
}
func (d *Daemon) ensureWorkDisk(ctx context.Context, vm *model.VMRecord) error {
func (d *Daemon) ensureWorkDisk(ctx context.Context, vm *model.VMRecord, image model.Image) error {
if exists(vm.Runtime.WorkDiskPath) {
return nil
}
if exists(image.WorkSeedPath) {
if err := system.CopyFilePreferClone(image.WorkSeedPath, vm.Runtime.WorkDiskPath); err != nil {
return err
}
seedInfo, err := os.Stat(image.WorkSeedPath)
if err != nil {
return err
}
if vm.Spec.WorkDiskSizeBytes < seedInfo.Size() {
return fmt.Errorf("requested work disk size %d is smaller than seed image %d", vm.Spec.WorkDiskSizeBytes, seedInfo.Size())
}
if vm.Spec.WorkDiskSizeBytes > seedInfo.Size() {
if err := system.ResizeExt4Image(ctx, d.runner, vm.Runtime.WorkDiskPath, vm.Spec.WorkDiskSizeBytes); err != nil {
return err
}
}
return nil
}
if _, err := d.runner.Run(ctx, "truncate", "-s", strconv.FormatInt(vm.Spec.WorkDiskSizeBytes, 10), vm.Runtime.WorkDiskPath); err != nil {
return err
}
@ -936,15 +955,6 @@ func (d *Daemon) cleanupRuntime(ctx context.Context, vm model.VMRecord, preserve
return err
}
}
if vm.Runtime.TapDevice != "" {
_, _ = d.runner.RunSudo(ctx, "ip", "link", "del", vm.Runtime.TapDevice)
}
if vm.Runtime.APISockPath != "" {
_ = os.Remove(vm.Runtime.APISockPath)
}
if vm.Runtime.VSockPath != "" {
_ = os.Remove(vm.Runtime.VSockPath)
}
snapshotErr := d.cleanupDMSnapshot(ctx, dmSnapshotHandles{
BaseLoop: vm.Runtime.BaseLoop,
COWLoop: vm.Runtime.COWLoop,
@ -952,10 +962,20 @@ func (d *Daemon) cleanupRuntime(ctx context.Context, vm model.VMRecord, preserve
DMDev: vm.Runtime.DMDev,
})
featureErr := d.cleanupCapabilityState(ctx, vm)
if !preserveDisks && vm.Runtime.VMDir != "" {
return errors.Join(snapshotErr, featureErr, os.RemoveAll(vm.Runtime.VMDir))
var tapErr error
if vm.Runtime.TapDevice != "" {
tapErr = d.releaseTap(ctx, vm.Runtime.TapDevice)
}
return errors.Join(snapshotErr, featureErr)
if vm.Runtime.APISockPath != "" {
_ = os.Remove(vm.Runtime.APISockPath)
}
if vm.Runtime.VSockPath != "" {
_ = os.Remove(vm.Runtime.VSockPath)
}
if !preserveDisks && vm.Runtime.VMDir != "" {
return errors.Join(snapshotErr, featureErr, tapErr, os.RemoveAll(vm.Runtime.VMDir))
}
return errors.Join(snapshotErr, featureErr, tapErr)
}
func clearRuntimeHandles(vm *model.VMRecord) {