Re: consider dropping defrag of journals on btrfs

[Lennart Poettering <lennart@xxxxxxxxxxxxxx>]

On Sa, 06.02.21 12:51, Chris Murphy (lists@xxxxxxxxxxxxxxxxx) wrote:

> The original commit description only mentions COW, it doesn't mention
> being predicated on nodatacow. In effect commit
> f27a386430cc7a27ebd06899d93310fb3bd4cee7 is obviated by commit
> 3a92e4ba470611ceec6693640b05eb248d62e32d four months later. I don't
> think they were ever intended to be used together, and combining them
> seems accidental.

Nah, both commits are for a common goal: make access time behaviour
OK'ish on btrfs, where it otherwise is terrible (on rotating media
particularly).

It's optimized for access times, not for minimal iops.

I'd be totally open to revisit this all, and take iops more into
account, but again, we'd need a bit of profiling that compares access
times, iops, and stuff with and without this, on rotating and ssd.

Lennart

--
Lennart Poettering, Berlin
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