ZFS parallel object sync

[awasb]

zfs sync parallelism by ednadolski-ix · Pull Request #15197 · openzfs/zfs

These changes address some performance and scaling limitations in the sync path: Allow parallel syncing of >1 dataset/objset. Sync no more (and if possible no fewer) dnodes at a time than there ar...

github.com

This could be ... wow.

 

[winnielinnie]

Looks to be a performance boost for VMs and iSCSI mostly? (Speed of sync writes of 4K block/record sizes.)

 

[HoneyBadger]

Looks to be a performance boost for VMs and iSCSI mostly? (Speed of sync writes of 4K block/record sizes.)

Anything that syncs multiple ZFS objects (multiple zvols, files across different datasets) should benefit from this, and pretty healthily too:

Code:

fio w/12x zvols prior to changes:
Run status group 0 (all jobs):
WRITE: bw=1267MiB/s (1328MB/s), 1267MiB/s-1267MiB/s (1328MB/s-1328MB/s), io=148GiB (159GB), run=120009-120009msec

fio with changes applied:
Run status group 0 (all jobs):
WRITE: bw=2380MiB/s (2495MB/s), 2380MiB/s-2380MiB/s (2495MB/s-2495MB/s), io=279GiB (299GB), run=120007-120007msec