Btrfs In Linux 6.8 Transitions Metadata Processing To Using Folios

[phoronix]

Phoronix: Btrfs In Linux 6.8 Transitions Metadata Processing To Using Folios

While not as notable as the Bcachefs additions, more work on XFS online repair, and other file-system updates for Linux 6.8, the Btrfs file-system driver changes for Linux 6.8 were merged last week...

https://www.phoronix.com/news/Linux-6.8-Btrfs

[timofonic]

Why are Folios a so hot abd interesting?

Why not other filesystems adopt it too?

[S.Pam]

Why are Folios a so hot abd interesting?

Why not other filesystems adopt it too?

Folios are, as I understand it, a kind of compound memory page. So instead of dealing with 4KiB pages, larger 'folios' can be used. Saves resources and should be faster. Kind of like hugepages.

[CommunityMember]

Why are Folios a so hot abd interesting?

There are performance advantages of using large "page" sizes for some use cases, and folios simplifies that use (so additional performance advantages).

Why not other filesystems adopt it too?

Some have already have (as I recall, XFS starting using folios for a subset of it's operations as part of the first patch series), more are targeted to do so in the future where it makes sense.

[cynic]

There are performance advantages of using large "page" sizes for some use cases, and folios simplifies that use (so additional performance advantages).



Some have already have (as I recall, XFS starting using folios for a subset of it's operations as part of the first patch series), more are targeted to do so in the future where it makes sense.

If I recall correct, ext4 is already using folios

[timofonic]

If I recall correct, ext4 is already using folios

And Bcachefs?

[cynic]

And Bcachefs?

haven't followed that fs, honestly. I'm not a big fan of its creator (altough I recognize this is not a rational reason)

[timofonic]

haven't followed that fs, honestly. I'm not a big fan of its creator (altough I recognize this is not a rational reason)

It seems Folios are used in place of extent buffers, but it's known that the performance can currently drop by a few percent for metadata-heavy workloads. However, large folios aren't yet enabled pending more testing.

I didn't research enough of it.

[varikonniemi]

Why was this merged with few percent performance degradation? The old model was not even deprecated!

Somehow i get the feeling that this change is needed to push forward their work of finally fixing up the raid hole in the future. But if it's so, it should not be merged before to hide the nastiness the raid hole fix necessitates. Or alternatively, if the "large folio" work coming will fix the performance issue, it should have been merged all at once.

[coder]

I'm surprised to hear folios reducing performance. I thought the underlying motivation was to improve it!