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

["Wodkowski, PawelX" <pawelx.wodkowski@intel.com>]

> -----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);