Re: [PATCH 00/12] btrfs: remap tree

[Mark Harmstone <maharmstone@meta.com>]

It looks like one of the nice side-effects of this patchset is a ~7% 
improvement in balance speed. These figures are from an NVMe drive, 
freshly rsync'd, with 69GB of 236GB used.

Without remap-tree, first time:
balanced 71 data chunks in 556s (= 7.8s each)
balanced 2 metadata chunks in 3s (= 1.5s each)

Without remap-tree, second time:
balanced 70 data chunks in 574s (= 8.2s each)
balanced 2 metadata chunks in 3s (= 1.5s each)

(same FS after being converted with btrfstune)
With remap-tree, first time:
balanced 71 data chunks in 533s (= 7.5s each)
balanced 2 metadata chunks in 5s (= 2.5s each)

With remap-tree, second time:
balanced 71 data chunks in 527s (= 7.4s each)
balanced 2 metadata chunks in 7s (= 3.5s each)

I've included the metadata balances as well, but I think they're too 
quick to be statistically significant.

I ran the balances twice because the remap-tree version has the 
potential to take longer the second time, as the move_existing_remaps() 
code will be called.

Mark