Message-ID: <51344F54.8060809@gmail.com>
Date: Mon, 04 Mar 2013 15:37:56 +0800
From: Cong Wang <xiyou.wangcong@gmail.com>
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To: Eliezer Tamir <eliezer.tamir@linux.jf.intel.com>
CC: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Dave Miller <davem@davemloft.net>,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        e1000-devel@lists.sourceforge.net,
        Willem de Bruijn <willemb@google.com>,
        Andi Kleen <andi@firstfloor.org>, HPA <hpa@zytor.com>,
        Eliezer Tamir <eliezer@tamir.org.il>
Subject: Re: [RFC PATCH 0/5] net: low latency Ethernet device polling
References: <20130227175549.10611.82188.stgit@gitlad.jf.intel.com>
In-Reply-To: <20130227175549.10611.82188.stgit@gitlad.jf.intel.com>
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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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