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From: Michael Qiu <michael.qiu@intel.com>
To: dev@dpdk.org
Subject: [dpdk-dev] [PATCH] Avoid possible memory cpoy when sort hugepages
Date: Wed, 10 Dec 2014 10:25:41 +0800
Message-ID: <1418178341-4193-1-git-send-email-michael.qiu@intel.com> (raw)

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

             reply	other threads:[~2014-12-10  2:26 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-10  2:25 Michael Qiu [this message]
2014-12-10 10:41 ` Bruce Richardson
2014-12-10 10:59   ` Qiu, Michael
2014-12-10 11:08     ` Ananyev, Konstantin
2014-12-10 17:58       ` Jay Rolette
     [not found]         ` <2601191342CEEE43887BDE71AB977258213BED0C@IRSMSX105.ger.corp.intel.com>
2014-12-10 18:39           ` Ananyev, Konstantin
2014-12-10 21:36             ` Jay Rolette
2014-12-11  1:44               ` Qiu, Michael

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