Re: [PATCH 5/7] xfs: implement block reservation accounting for btrees we're staging

Darrick J. Wong
2023-11-28T17:02:22Z

On Mon, Nov 27, 2023 at 09:41:28PM -0800, Christoph Hellwig wrote:
> On Mon, Nov 27, 2023 at 02:34:51PM -0800, Darrick J. Wong wrote:
> > That had a noticeable effect on performance straight after mounting
> > because touching /any/ btree would result in splits. IIRC Dave and I
> > decided that repair should generate btree blocks that were 75% full
> > unless space was tight. We defined tight as ~10% free to avoid repair
> > failures and settled on 3/32 to avoid div64.
> >
> > IOWs, we mostly pulled it out of thin air. ;)
>
> Maybe throw a little comment about this in.

Yeah, I'll paste the sordid history into the commit message when I
change the code to use div_u64.

--D