netdev - Re: Fwd: Packet mmap: TX RING and zero copy

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Date:	Fri, 5 Sep 2008 17:30:39 +0200
From:	"Johann Baudy" <johaahn@...il.com>
To:	"Evgeniy Polyakov" <johnpol@....mipt.ru>
Cc:	netdev@...r.kernel.org
Subject: Re: Fwd: Packet mmap: TX RING and zero copy

Hi Evgeniy,


> Well, udp_sendpage() needs to be extended to only append page when there
> is anough free space there, otherwise push given frame and create next
> packet.
>
Ok, I'll do a patch and let you know result.

>
> I meant you get a pointer by mapping some file in tmpfs (for example)
> and then use some offset variable to store where you put your last data
> (either packet header, or data itself), so that any subsequent write to
> that area (either new packet header or dma data placement) would put
> data just after the previous chunk. Thus after you have put number of
> headers and appropriate data chunks, you could call sendfile() and reset
> offset to the beginning of the mapped area.

If I understand well, there is no link between start of ethernet frame
and packet header ?
App protocol must support packet loss ^^

Thanks,
Johann

-- 
Johann Baudy
johaahn@...il.com
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