Re: [RFC] [TCP 1/3] tcp: Add MSG_NEW_PACKET flag to indicatepreferable packet boundaries

From: Eric Dumazet
Date: Fri Jun 29 2012 - 11:11:06 EST


On Fri, 2012-06-29 at 16:54 +0200, Andreas Gruenbacher wrote:
> The MSG_NEW_PACKET flag indicates to sendmsg / sendpage that the message or
> page should be put into a new packet even when there is still room left in the
> previous packet.
>
> In the tcp protocol, messages which are not sent immediately are queued. When
> more data is sent, it will be added to the last segment in that queue until
> that segment is "full" whenever possible; only then is a new segment added.
> Right now, there is no way to indicate when tcp should start a new segment.
> The new flag allows to control that.
>
> Signed-off-by: Andreas Gruenbacher <agruen@xxxxxxxxxx>
> ---

I don't understand how maintaining any message boundaries at sender can
prevent any middlebox or the receiver to coalesce frames to any
boundaries it prefers ?



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