From: Eric Dumazet <dada1@cosmosbay.com>
To: "David S. Miller" <davem@davemloft.net>,
"YOSHIFUJI Hideaki / 吉藤英明" <yoshfuji@linux-ipv6.org>
Cc: Linux Netdev List <netdev@vger.kernel.org>
Subject: [TCP] IPV6 : Change a divide into a right shift in tcp_v6_send_ack()
Date: Fri, 21 Dec 2007 07:03:58 +0100 [thread overview]
Message-ID: <476B574E.80601@cosmosbay.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 211 bytes --]
Because tot_len is signed in tcp_v6_send_ack(), tot_len/4 forces compiler
to emit an integer divide, while we can help it to use a right shift,
less expensive.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
[-- Attachment #2: tcp_ipv6.patch --]
[-- Type: text/plain, Size: 415 bytes --]
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0268e11..92f0fda 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1124,7 +1124,7 @@ static void tcp_v6_send_ack(struct tcp_timewait_sock *tw,
memset(t1, 0, sizeof(*t1));
t1->dest = th->source;
t1->source = th->dest;
- t1->doff = tot_len/4;
+ t1->doff = tot_len >> 2;
t1->seq = htonl(seq);
t1->ack_seq = htonl(ack);
t1->ack = 1;
next reply other threads:[~2007-12-21 6:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-21 6:03 Eric Dumazet [this message]
2007-12-21 6:50 ` [TCP] IPV6 : Change a divide into a right shift in tcp_v6_send_ack() YOSHIFUJI Hideaki / 吉藤英明
2007-12-21 7:06 ` Eric Dumazet
[not found] ` <20071221.162833.82587283.yoshfuji@linux-ipv6.org>
2007-12-21 7:39 ` Eric Dumazet
2007-12-21 7:44 ` YOSHIFUJI Hideaki / 吉藤英明
2007-12-21 7:50 ` Eric Dumazet
2007-12-21 9:46 ` David Miller
2007-12-21 8:11 ` Eric Dumazet
2007-12-21 11:26 ` Jeff Garzik
2007-12-21 11:57 ` David Miller
2007-12-21 12:18 ` Jeff Garzik
2007-12-21 7:21 ` Ilpo Järvinen
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