netdev - [RFC PATCH] net, rps: bypass enqueue_to

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Message-Id: <1387371816-32476-1-git-send-email-zwu.kernel@gmail.com>
Date:	Wed, 18 Dec 2013 21:03:36 +0800
From:	Zhi Yong Wu <zwu.kernel@...il.com>
To:	therbert@...gle.com
Cc:	netdev@...r.kernel.org, Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
Subject: [RFC PATCH] net, rps: bypass enqueue_to_backlog()

From: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>

When local cpu is just target cpu which will handle network soft irq,
the packet should be directly injected to network stack, by bypassing
enqueue_to_backlog(), it can speed up the packet processing.

HI, guys

I checked the first several versions of RPS patch which seemed to have
this condition determination, but why was it removed later? Do i miss
anything? if yes, please correct me, thanks.

Signed-off-by: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
---
 net/core/dev.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index c482fe8..d29d61f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3693,7 +3693,7 @@ int netif_receive_skb(struct sk_buff *skb)
 
 		cpu = get_rps_cpu(skb->dev, skb, &rflow);
 
-		if (cpu >= 0) {
+		if ((cpu >= 0) && (cpu != raw_smp_processor_id())) {
 			ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
 			rcu_read_unlock();
 			return ret;
-- 
1.7.6.5

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