netdev - [RFC net-next PATCH V1 8/9] net: increase frag queue hash size and cache-line

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Date:	Fri, 23 Nov 2012 14:08:42 +0100
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Florian Westphal <fw@...len.de>
Cc:	Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Thomas Graf <tgraf@...g.ch>, Cong Wang <amwang@...hat.com>,
	"Patrick McHardy" <kaber@...sh.net>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Herbert Xu <herbert@...dor.hengli.com.au>
Subject: [RFC net-next PATCH V1 8/9] net: increase frag queue hash size and
	cache-line

Increase frag queue hash size and assure cache-line alignment to
avoid false sharing.  Hash size is set to 256, because I have
observed 206 frag queues in use at 4x10G with packet size 4416 bytes.

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---

 include/net/inet_frag.h |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 1efec6b..5054228 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -49,13 +49,12 @@ struct inet_frag_queue {
 	u16			max_size;
 };
 
-#define INETFRAGS_HASHSZ		64
-
+#define INETFRAGS_HASHSZ	256
 
 struct inet_frag_bucket {
 	struct hlist_head	chain;
 	spinlock_t		chain_lock;
-};
+} ____cacheline_aligned_in_smp;
 
 struct inet_frags {
 	struct inet_frag_bucket	hash[INETFRAGS_HASHSZ];

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