Re: [dpdk-dev] [PATCH] replaced O(n^2) sort in sort_by_physaddr() with qsort() from standard library

[Jay Rolette <rolette@infiniteio.com>]

Because it doesn't work correctly :-)

On Mon, Dec 15, 2014 at 3:05 AM, Wodkowski, PawelX <
pawelx.wodkowski@intel.com> wrote:
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jay Rolette
> > Sent: Thursday, December 11, 2014 5:06 PM
> > To: Dev
> > Subject: [dpdk-dev] [PATCH] replaced O(n^2) sort in sort_by_physaddr()
> with
> > qsort() from standard library
> >
> > Signed-off-by: Jay Rolette <rolette@infiniteio.com>
> > ---
> >  lib/librte_eal/linuxapp/eal/eal_memory.c | 59
> > +++++++++++---------------------
> >  1 file changed, 20 insertions(+), 39 deletions(-)
> >
> > diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> > b/lib/librte_eal/linuxapp/eal/eal_memory.c
> > index bae2507..3656515 100644
> > --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> > +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> > @@ -670,6 +670,25 @@ error:
> >   return -1;
> >  }
> >
> > +static int
> > +cmp_physaddr(const void *a, const void *b)
> > +{
> > +#ifndef RTE_ARCH_PPC_64
> > + const struct hugepage_file *p1 = (const struct hugepage_file *)a;
> > + const struct hugepage_file *p2 = (const struct hugepage_file *)b;
> > +#else
> > + // PowerPC needs memory sorted in reverse order from x86
> > + const struct hugepage_file *p1 = (const struct hugepage_file *)b;
> > + const struct hugepage_file *p2 = (const struct hugepage_file *)a;
> > +#endif
> > + if (p1->physaddr < p2->physaddr)
> > + return -1;
> > + else if (p1->physaddr > p2->physaddr)
> > + return 1;
> > + else
> > + return 0;
> > +}
> > +
>
> Why not simply
>
> return (int)(p1->physaddr - p2->physaddr);
>
>