Re: [PATCH 4/5] xfs: speed up directory bestfree block scanning

Dave Chinner
2019-08-29T09:31:22Z

On Thu, Aug 29, 2019 at 01:25:01AM -0700, Christoph Hellwig wrote:
> Actually, another comment:
>
> > + /* Scan the free entry array for a large enough free space. */
> > + do {
> > + if (be16_to_cpu(bests[findex]) != NULLDATAOFF &&
>
> This could be changed to:
>
> if (bests[findex] != cpu_to_be16(NULLDATAOFF) &&
>
> which might lead to slightly better code generation.

I don't think it will make any difference because the very next
comparison in the if() statement needs the cpu order bests[findex]
value because its a >= check. Hence we have to calculate it anyway,
and the compiler should be smart enough to only evaluate it once...

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com