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

[Jay Rolette]

Signed-off-by: Jay Rolette <rolette at 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;
+}
+
 /*
  * 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;
 }

--