Following conversation in
http://dpdk.org/ml/archives/dev/2015-September/023230.html :
On 17/12/2014 13:31, rolette at infiniteio.com (Jay Rolette) wrote:
> Signed-off-by: Jay Rolette <rolette at infiniteio.com>
> ---
Update commit title/description, maybe something like:
eal/linux: use qsort for sorting hugepages
Replace O(n^2) sort in sort_by_physaddr() with qsort() from standard
library
> 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;
> +}
> +
There were a couple of comments from Thomas about the comments style and
#ifdef:
- Comment style should be modified as per
http://dpdk.org/doc/guides/contributing/coding_style.html#c-comment-style
- Regarding the #ifdef, I agree with Jay that it is the current approach
in the file.
> /*
> * Sort the hugepg_tbl by physical address (lower addresses first on x86,
> * higher address first on powerpc). We use a slow algorithm, but we won't
> @@ -678,45 +697,7 @@ error:
> static int
> sort_by_physaddr(struct hugepage_file *hugepg_tbl, struct hugepage_info
> *hpi)
> {
> - unsigned i, j;
> - int compare_idx;
> - uint64_t compare_addr;
> - struct hugepage_file tmp;
> -
> - for (i = 0; i < hpi->num_pages[0]; i++) {
> - compare_addr = 0;
> - compare_idx = -1;
> -
> - /*
> - * browse all entries starting at 'i', and find the
> - * entry with the smallest addr
> - */
> - for (j=i; j< hpi->num_pages[0]; j++) {
> -
> - if (compare_addr == 0 ||
> -#ifdef RTE_ARCH_PPC_64
> - hugepg_tbl[j].physaddr > compare_addr) {
> -#else
> - hugepg_tbl[j].physaddr < compare_addr) {
> -#endif
> - compare_addr = hugepg_tbl[j].physaddr;
> - compare_idx = j;
> - }
> - }
> -
> - /* should not happen */
> - if (compare_idx == -1) {
> - RTE_LOG(ERR, EAL, "%s(): error in physaddr sorting\n",
> __func__);
> - return -1;
> - }
> -
> - /* swap the 2 entries in the table */
> - memcpy(&tmp, &hugepg_tbl[compare_idx],
> - sizeof(struct hugepage_file));
> - memcpy(&hugepg_tbl[compare_idx], &hugepg_tbl[i],
> - sizeof(struct hugepage_file));
> - memcpy(&hugepg_tbl[i], &tmp, sizeof(struct hugepage_file));
> - }
> + qsort(hugepg_tbl, hpi->num_pages[0], sizeof(struct hugepage_file),
> cmp_physaddr);
> return 0;
> }
Why not just remove sort_by_physaddr() and call qsort() directly?
Sergio
