Disregard that, brainfart on my side.
Mathieu - wrote:
> Anton Lindqvist wrote:
> > Hi,
> > If the elements argument passed to hashinit() is a power of 2 there's no
> > need to find the closest power of 2 that can fit all elements since
> > elements == hashsize will always be true. During boot of a stock amd64
> > kernel running inside vmd 80% of the calls to hashinit() includes a
> > power of 2 size.
> >
> > Comments? OK?
>
>
> Hi,
>
> Dunno how much a win it is. But anyhow this will blow in hashfree as
> hashsize won't be the same.
>
>
> Mathieu.
>
>
>
> >
> > Index: kern/kern_subr.c
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/kern_subr.c,v
> > retrieving revision 1.49
> > diff -u -p -r1.49 kern_subr.c
> > --- kern/kern_subr.c 14 Feb 2017 10:31:15 -0000 1.49
> > +++ kern/kern_subr.c 28 Apr 2018 20:21:40 -0000
> > @@ -163,8 +163,11 @@ hashinit(int elements, int type, int fla
> >
> > if (elements <= 0)
> > panic("hashinit: bad cnt");
> > - for (hashsize = 1; hashsize < elements; hashsize <<= 1)
> > - continue;
> > + if ((elements & (elements - 1)) == 0)
> > + hashsize = elements;
> > + else
> > + for (hashsize = 1; hashsize < elements; hashsize <<= 1)
> > + continue;
> > hashtbl = mallocarray(hashsize, sizeof(*hashtbl), type, flags);
> > if (hashtbl == NULL)
> > return NULL;
> >
>
