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system: mkfs work disks with lazy_itable_init + lazy_journal_init

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mkfs.ext4 zeroes the entire inode table and journal at format time
unless told otherwise. On an 8 GiB work disk that's roughly 500-700ms
of host CPU/IO per 'banger vm create', for a one-time small per-write
penalty inside the guest the first time it touches an unwritten
inode that nobody can perceive.

Centralise the canonical mkfs -E option list as
system.MkfsExtraOptions and use it everywhere banger calls mkfs.ext4
on a VM-internal image: the no-seed work disk, MaterializeWorkDisk,
BuildWorkSeedImage, and the imagepull rootfs builder. The work-disk
paths feed vm create directly; the others are one-off but still
benefit from the faster format.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Thales Maciel 2026-04-26 21:32:57 -03:00
parent 74e5a7cedb
commit 74a2d064fd
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GPG key ID: 33112E6833C34679
3 changed files with 18 additions and 7 deletions
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2
internal/daemon/vm_disk.go
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@ -122,7 +122,7 @@ func (s *VMService) ensureWorkDisk(ctx context.Context, vm *model.VMRecord, imag
if _, err := s.runner.Run(ctx, "truncate", "-s", strconv.FormatInt(vm.Spec.WorkDiskSizeBytes, 10), vm.Runtime.WorkDiskPath); err != nil {
return workDiskPreparation{}, err
}
if _, err := s.runner.Run(ctx, "mkfs.ext4", "-F", "-E", "root_owner=0:0", vm.Runtime.WorkDiskPath); err != nil {
if _, err := s.runner.Run(ctx, "mkfs.ext4", "-F", "-E", system.MkfsExtraOptions, vm.Runtime.WorkDiskPath); err != nil {
return workDiskPreparation{}, err
}
return workDiskPreparation{}, nil