[dpdk-dev] [PATCH] Avoid possible memory cpoy when sort hugepages

[Michael Qiu <michael.qiu@intel.com>]

When the first address is the compared address in the loop,
it will also do memory copy, which is meaningless,
worse more, when hugepg_tbl is mostly in order. This should
be a big deal in large hugepage memory systerm(like hunderd
or thousand GB).

Meanwhile smallest_idx never be a value of -1,so remove this check.

This patch also includes some coding style fix.

Signed-off-by: Michael Qiu <michael.qiu@intel.com>
---
 lib/librte_eal/linuxapp/eal/eal_memory.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
index e6cb919..700aba2 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -678,14 +678,13 @@ error:
 static int
 sort_by_physaddr(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi)
 {
-	unsigned i, j;
-	int compare_idx;
+	unsigned i, j, 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;
+		compare_idx = i;
 
 		/*
 		 * browse all entries starting at 'i', and find the
@@ -704,11 +703,9 @@ sort_by_physaddr(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi)
 			}
 		}
 
-		/* should not happen */
-		if (compare_idx == -1) {
-			RTE_LOG(ERR, EAL, "%s(): error in physaddr sorting\n", __func__);
-			return -1;
-		}
+		/* avoid memory copy when the first entry is the compared */
+		if (compare_idx == i)
+			continue;
 
 		/* swap the 2 entries in the table */
 		memcpy(&tmp, &hugepg_tbl[compare_idx],
-- 
1.9.3