From: David Miller <davem@davemloft.net>
To: hkchu@google.com
Cc: netdev@vger.kernel.org
Subject: Re: Socket buffer sizes with autotuning
Date: Wed, 07 May 2008 14:20:13 -0700 (PDT) [thread overview]
Message-ID: <20080507.142013.219220793.davem@davemloft.net> (raw)
In-Reply-To: <d1c2719f0805071154t20004e9drecd3d9b7b9b3470c@mail.gmail.com>
From: "Jerry Chu" <hkchu@google.com>
Date: Wed, 7 May 2008 11:54:01 -0700
> This is one of many things about skb that I still don't completely understand.
> Why in tcp_transmit_skb() we'll have to pskb_copy() if skb_cloned()?
The other clone holder owns the packet header area. All packets on
the retransmit queue of TCP are headerless. The call sites down
into the device add the headers.
Therefore we cannot have two paths modifying the headers at the same
time.
> Can't we clone a skb mulitple times? Is it due to some special optimization
> from skb->fclone stuff... that imposes this restriction?
No, it has nothing to do with fclone. It has to do with what instance
owns the packet header area in front of the user's TCP data.
next prev parent reply other threads:[~2008-05-07 21:20 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-23 23:29 Socket buffer sizes with autotuning Jerry Chu
2008-04-24 16:32 ` John Heffner
2008-04-25 0:49 ` Jerry Chu
2008-04-25 6:46 ` David Miller
2008-04-25 21:29 ` Jerry Chu
2008-04-25 21:35 ` David Miller
2008-04-28 18:30 ` Jerry Chu
2008-04-28 19:21 ` John Heffner
2008-04-28 20:44 ` Jerry Chu
2008-04-28 23:22 ` [PATCH 1/2] [NET]: Allow send-limited cwnd to grow up to max_burst when gso disabled John Heffner
2008-04-28 23:22 ` [PATCH 2/2] [NET]: Limit cwnd growth when deferring for GSO John Heffner
[not found] ` <d1c2719f0804281338j3984cf2bga31def0c2c1192a1@mail.gmail.com>
2008-04-28 23:28 ` Socket buffer sizes with autotuning John Heffner
2008-04-28 23:35 ` David Miller
2008-04-29 2:20 ` Jerry Chu
2008-04-25 7:05 ` David Miller
2008-05-07 3:57 ` Jerry Chu
2008-05-07 4:27 ` David Miller
2008-05-07 18:36 ` Jerry Chu
2008-05-07 21:18 ` David Miller
2008-05-08 1:37 ` Jerry Chu
2008-05-08 1:43 ` David Miller
2008-05-08 3:33 ` Jerry Chu
2008-05-12 22:22 ` Jerry Chu
2008-05-12 22:29 ` David Miller
2008-05-12 22:31 ` David Miller
2008-05-13 3:56 ` Jerry Chu
2008-05-13 3:58 ` David Miller
2008-05-13 4:00 ` Jerry Chu
2008-05-13 4:02 ` David Miller
2008-05-17 1:13 ` Jerry Chu
2008-05-17 1:29 ` David Miller
2008-05-17 1:47 ` Jerry Chu
2008-05-12 22:58 ` Jerry Chu
2008-05-12 23:01 ` David Miller
2008-05-07 4:28 ` David Miller
2008-05-07 18:54 ` Jerry Chu
2008-05-07 21:20 ` David Miller [this message]
2008-05-08 0:16 ` Jerry Chu
[not found] <d1c2719f0804241829s1bc3f41ejf7ebbff73ed96578@mail.gmail.com>
2008-04-25 7:06 ` Andi Kleen
2008-04-25 7:28 ` David Miller
2008-04-25 7:48 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2008-04-23 0:38 Rick Jones
2008-04-23 2:17 ` John Heffner
2008-04-23 3:59 ` David Miller
2008-04-23 16:32 ` Rick Jones
2008-04-23 16:58 ` John Heffner
2008-04-23 17:24 ` Rick Jones
2008-04-23 17:41 ` John Heffner
2008-04-23 17:46 ` Rick Jones
2008-04-24 22:21 ` Andi Kleen
2008-04-24 22:39 ` John Heffner
2008-04-25 1:28 ` David Miller
[not found] ` <65634d660804242234w66455bedve44801a98e3de9d9@mail.gmail.com>
2008-04-25 6:36 ` David Miller
2008-04-25 7:42 ` Tom Herbert
2008-04-25 7:46 ` David Miller
2008-04-28 17:51 ` Tom Herbert
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