DPDK patches and discussions
 help / color / mirror / Atom feed
From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
To: "dev@dpdk.org" <dev@dpdk.org>
Cc: Hayato Momma <h-momma@ce.jp.nec.com>
Subject: [dpdk-dev] [memnic PATCH 6/7] pmd: add branch hint in recv/xmit
Date: Thu, 11 Sep 2014 07:51:46 +0000
Message-ID: <7F861DC0615E0C47A872E6F3C5FCDDBD011A99A8@BPXM14GP.gisp.nec.co.jp> (raw)

From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>

To reduce instruction cache miss, add branch condition hints into
recv/xmit functions. This improves a bit performance.

We can see performance improvements with memnic-tester.
Using Xeon E5-2697 v2 @ 2.70GHz, 4 vCPU.
 size |  before  |  after
   64 | 5.54Mpps | 5.55Mpps
  128 | 5.46Mpps | 5.44Mpps
  256 | 5.21Mpps | 5.22Mpps
  512 | 4.50Mpps | 4.52Mpps
 1024 | 3.71Mpps | 3.73Mpps
 1280 | 3.21Mpps | 3.22Mpps
 1518 | 2.92Mpps | 2.93Mpps

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Reviewed-by: Hayato Momma <h-momma@ce.jp.nec.com>
---
 pmd/pmd_memnic.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/pmd/pmd_memnic.c b/pmd/pmd_memnic.c
index dbe5033..cc0ae25 100644
--- a/pmd/pmd_memnic.c
+++ b/pmd/pmd_memnic.c
@@ -289,26 +289,26 @@ static uint16_t memnic_recv_pkts(void *rx_queue,
 	int idx, next;
 	struct rte_eth_stats *st = &adapter->stats[rte_lcore_id()];
 
-	if (!adapter->nic->hdr.valid)
+	if (unlikely(!adapter->nic->hdr.valid))
 		return 0;
 
 	pkts = bytes = errs = 0;
 	idx = adapter->up_idx;
 	for (nr = 0; nr < nb_pkts; nr++) {
 		p = &data->packets[idx];
-		if (p->status != MEMNIC_PKT_ST_FILLED)
+		if (unlikely(p->status != MEMNIC_PKT_ST_FILLED))
 			break;
 		/* prefetch the next area */
 		next = idx;
-		if (++next >= MEMNIC_NR_PACKET)
+		if (unlikely(++next >= MEMNIC_NR_PACKET))
 			next = 0;
 		rte_prefetch0(&data->packets[next]);
-		if (p->len > framesz) {
+		if (unlikely(p->len > framesz)) {
 			errs++;
 			goto drop;
 		}
 		mb = rte_pktmbuf_alloc(adapter->mp);
-		if (!mb)
+		if (unlikely(!mb))
 			break;
 
 		rte_memcpy(rte_pktmbuf_mtod(mb, void *), p->data, p->len);
@@ -350,7 +350,7 @@ static uint16_t memnic_xmit_pkts(void *tx_queue,
 	uint64_t pkts, bytes, errs;
 	uint32_t framesz = adapter->framesz;
 
-	if (!adapter->nic->hdr.valid)
+	if (unlikely(!adapter->nic->hdr.valid))
 		return 0;
 
 	pkts = bytes = errs = 0;
@@ -360,7 +360,7 @@ static uint16_t memnic_xmit_pkts(void *tx_queue,
 		struct rte_mbuf *sg;
 		void *ptr;
 
-		if (pkt_len > framesz) {
+		if (unlikely(pkt_len > framesz)) {
 			errs++;
 			break;
 		}
@@ -379,7 +379,7 @@ retry:
 			goto retry;
 		}
 
-		if (idx != ACCESS_ONCE(adapter->down_idx)) {
+		if (unlikely(idx != ACCESS_ONCE(adapter->down_idx))) {
 			/*
 			 * host freed this and got false positive,
 			 * need to recover the status and retry.
@@ -388,7 +388,7 @@ retry:
 			goto retry;
 		}
 
-		if (++idx >= MEMNIC_NR_PACKET)
+		if (unlikely(++idx >= MEMNIC_NR_PACKET))
 			idx = 0;
 		adapter->down_idx = idx;
 
-- 
1.8.3.1

                 reply	other threads:[~2014-09-11  7:54 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=7F861DC0615E0C47A872E6F3C5FCDDBD011A99A8@BPXM14GP.gisp.nec.co.jp \
    --to=h-shimamoto@ct.jp.nec.com \
    --cc=dev@dpdk.org \
    --cc=h-momma@ce.jp.nec.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ https://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git