Re: ResourceOwner refactoring

On Thu, Nov 19, 2020 at 10:16 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>
> On Wed, Nov 18, 2020 at 10:50:08AM +0200, Heikki Linnakangas wrote:
> > If RESOWNER_ARRAY_STATS is increased to 16, all the lookups fit in the
> > array. But I haven't done any benchmarking to see which is faster.
>
> My gut tells me that your guess is right, but it would be better to be
> sure.
>
> > BTW, I think there would be an easy win in the hashing codepath, by changing
> > to a cheaper hash function. Currently, with or without this patch, we use
> > hash_any(). Changing that to murmurhash32() or something similar would be a
> > drop-in replacement.
>
> Good idea.

+1, and +1 for this refactoring.

I just saw a minor issue in a comment while reviewing the patch:

[...]
+ /* Is there space in the hash? If not, enlarge it. */

/* Double the capacity of the array (capacity must stay a power of 2!) */
- newcap = (oldcap > 0) ? oldcap * 2 : RESARRAY_INIT_SIZE;
[...]

The existing comment is kept as-is, but it should mention that it's
now the hash capacity that is increased.