Re: subr_kmem

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Hello Lars,

Lars Heidieker <lars%heidieker.de@localhost> wrote:
> slight improvement on kmem(9):
> 
> splitting the lookup table into two parts
> - this reduces the size of the lookup table -> touching less cache-lines
>     (e.g. on 64bit down from 4096b to 1024b + 64b)

Why do you think the split would result in touching fewer cache-lines?
Because of prefetch?  I do not really think it has a real effect.

> - expanding cache size up to PAGE_SIZE for larger then 4k PAGE_SIZE
> machines (without blowing up the size of the lookup table further)

I guess this is a part which gives you a tiny speedup.  However, these
sizes are quite large and we do not know the fill ratio - it may waste
quite a bit of memory, in favour of tiny speedup.

Do you have more data?  Otherwise, I am not really sure if these changes
are a good idea..

-- 
Mindaugas