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From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: yanmin_zhang@linux.intel.com, cl@linux-foundation.org,
	penberg@cs.helsinki.fi, netdev@vger.kernel.org, tj@kernel.org,
	alex.shi@intel.com, linux-kernel@vger.kernel.org,
	ling.ma@intel.com, tim.c.chen@intel.com,
	akpm@linux-foundation.org
Subject: Re: hackbench regression due to commit 9dfc6e68bfe6e
Date: Thu, 08 Apr 2010 00:20:11 -0700 (PDT)	[thread overview]
Message-ID: <20100408.002011.121977482.davem@davemloft.net> (raw)
In-Reply-To: <20100408.000557.180546976.davem@davemloft.net>

From: David Miller <davem@davemloft.net>
Date: Thu, 08 Apr 2010 00:05:57 -0700 (PDT)

> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Thu, 08 Apr 2010 09:00:19 +0200
> 
>> If run individually, the tests results are more what we would expect
>> (slow), but if machine runs the two set of process concurrently, each
>> group runs much faster...
> 
> BTW, I just discovered (thanks to the function graph tracer, woo hoo!)
> that loopback TCP packets get fully checksum validated on receive.
> 
> I'm trying to figure out why skb->ip_summed ends up being
> CHECKSUM_NONE in tcp_v4_rcv() even though it gets set to
> CHECKSUM_PARTIAL in tcp_sendmsg().

Ok, it looks like it's only ACK packets that have this problem,
but still :-)

It's weird that we have a special ip_dev_loopback_xmit() for for
ip_mc_output() NF_HOOK()s, which forces skb->ip_summed to
CHECKSUM_UNNECESSARY, but the actual normal loopback xmit doesn't
do that...

  reply	other threads:[~2010-04-08  7:20 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-25  8:40 hackbench regression due to commit 9dfc6e68bfe6e Alex Shi
2010-03-25 14:49 ` Christoph Lameter
2010-03-26  2:35   ` Alex Shi
2010-04-01  9:29     ` Zhang, Yanmin
2010-04-01 15:53       ` Christoph Lameter
2010-04-02  8:06         ` Zhang, Yanmin
2010-04-05 13:54           ` Christoph Lameter
2010-04-05 17:30             ` Pekka Enberg
2010-04-06  1:27               ` Tejun Heo
2010-04-06  8:28                 ` Zhang, Yanmin
2010-04-06 15:41                   ` Christoph Lameter
2010-04-06 20:55                     ` Christoph Lameter
2010-04-06 22:10                       ` Eric Dumazet
2010-04-07  2:34                         ` Zhang, Yanmin
2010-04-07  6:39                           ` Eric Dumazet
2010-04-07  9:07                             ` Zhang, Yanmin
2010-04-07  9:20                               ` Eric Dumazet
2010-04-07 10:47                           ` Pekka Enberg
2010-04-07 16:30                           ` Christoph Lameter
2010-04-07 16:43                           ` Christoph Lameter
2010-04-07 16:49                             ` Pekka Enberg
2010-04-07 16:52                               ` Pekka Enberg
2010-04-07 18:20                                 ` Christoph Lameter
2010-04-07 18:25                                   ` Pekka Enberg
2010-04-07 18:25                                     ` Pekka Enberg
2010-04-07 19:30                                     ` Christoph Lameter
2010-04-07 18:38                                   ` Eric Dumazet
2010-04-08  1:05                                     ` Zhang, Yanmin
2010-04-08  4:59                                       ` Eric Dumazet
2010-04-08  5:39                                         ` Eric Dumazet
2010-04-08  7:00                                           ` Eric Dumazet
2010-04-08  7:05                                             ` David Miller
2010-04-08  7:20                                               ` David Miller [this message]
2010-04-08  7:25                                               ` Eric Dumazet
2010-04-08  7:54                                             ` Zhang, Yanmin
2010-04-08  7:54                                               ` Eric Dumazet
2010-04-08  8:09                                                 ` Eric Dumazet
2010-04-08 15:34                                           ` Christoph Lameter
2010-04-08 15:52                                             ` Eric Dumazet
2010-04-07 18:18                               ` Christoph Lameter
2010-04-08  7:18                             ` Zhang, Yanmin
2010-04-07  2:20                       ` Zhang, Yanmin
2010-04-07  0:58                     ` Zhang, Yanmin

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