Re: [PATCH 0/4] btrfs: some more speedups for directory logging/fsync

[David Sterba <dsterba@suse.cz>]

On Wed, Dec 15, 2021 at 12:19:57PM +0000, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> This patchset brings some more performance improvements for directory
> logging/fsync, by doing some changes to the logging algorithm to avoid
> logging dentries created in past transactions, which helps reducing a
> lot the amount of logged metadata, and therefore less IO as well for
> large directories.
> 
> It specially benefits the case when some dentries were removed, either
> due to file deletes or renames, where it can reduce the total time spent
> in an fsync by an order of magnitude even if the number of dentries removed
> is a small percentage of the total dentries in the directory (for e.g. as
> little as 1%, like in the test results of the changelog of patch 3/4).
> 
> This builds on top of my previous patchset to make directory logging copy
> only dir index keys and skip dir item keys, which has been on misc-next
> since the previous merge window closed.
> 
> Patches 1/4 and 3/4 are the changes that accomplish this, while patch 2/4
> is just preparation for patch 3/4, and patch 4/4 is more of a cleanup of
> old, unnecessary and unreliable logic. Test case generic/335 was recently
> updated in fstests, so that after applying patch 4/4 it passes.
> 
> Patch 3/4 contains in its changelog the test and results.
> 
> We are close to the 5.17 merge window, holiday season is approaching and
> there's already a significant change for directory logging coming to 5.17
> (log only dir index keys and skip dir item keys), so I think this patchset
> is better suited for the 5.18 merge window.

The for-5.17 has been branched, so this patchset is now in misc-next,
thanks.