linux-kernel - Re: [RFC PATCH 0/5] net: low latency Ethernet device polling

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Message-ID: <51344F54.8060809@gmail.com>
Date:	Mon, 04 Mar 2013 15:37:56 +0800
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Eliezer Tamir <eliezer.tamir@...ux.jf.intel.com>
CC:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	Dave Miller <davem@...emloft.net>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	e1000-devel@...ts.sourceforge.net,
	Willem de Bruijn <willemb@...gle.com>,
	Andi Kleen <andi@...stfloor.org>, HPA <hpa@...or.com>,
	Eliezer Tamir <eliezer@...ir.org.il>
Subject: Re: [RFC PATCH 0/5] net: low latency Ethernet device polling

On 02/28/2013 01:55 AM, Eliezer Tamir wrote:
>
> Open issues:
> 1. Find a way to avoid the need to change the sk and skb structs.
> One big disadvantage of how we do this right now is that when a device is
> removed, it's hard to prevent it from getting polled by a socket
> which holds a stale reference.
>
> 2. How do we decide which sockets are eligible to do busy polling?
> Do we add a socket option to control this?
> How do we provide sane defaults while allowing flexibility and performance?
>
> 3. Andi Kleen and HPA pointed out that using get_cycles() is not portable.
>
> 4. How and where do we call ndo_ll_poll from the socket code?
> One good place seems to be wherever the kernel puts the process to sleep,
> waiting for more data, but this makes doing something intelligent about
> poll (the system call) hard. From the perspective of how ndo_ll_poll
> itself is implemented this does not seem to matter.
>
> 5. I would like to hear suggestions on naming conventions and where
> to put the code that for now I have put in include/net/ll_poll.h
>


A dumb question: is bypassing tcpdump/netfilters/qdisc etc. what we 
always want? Isn't this a security issue?

Thanks!
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