Date: Wed, 5 Jun 2013 16:47:42 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: Chao Xu <caesarxuchao@gmail.com> Cc: freebsd-net@freebsd.org, adrian@freebsd.org Subject: Re: netmap on wireless NIC Message-ID: <20130605144742.GA38474@onelab2.iet.unipi.it> In-Reply-To: <CAKZq%2BrdZUyjg5eBAUjU_2ow-ffx-WYeoBqB40hDpW3tZbtZ7ug@mail.gmail.com> References: <CAKZq%2BrfJNRpvigA=4OXfvjhHm35XNJRpAk4ONHNudeG-sr=3YQ@mail.gmail.com> <20130605134507.GB38081@onelab2.iet.unipi.it> <CAKZq%2BrdZUyjg5eBAUjU_2ow-ffx-WYeoBqB40hDpW3tZbtZ7ug@mail.gmail.com>
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On Wed, Jun 05, 2013 at 09:28:00AM -0500, Chao Xu wrote: > Thank you Adrian and Luigi. My goal is to reduce the latency, i.e. get the > packet as soon as it arrives on the NIC, and send the packet from user > space to NIC quickly. I think netmap will help because it skips the socket > layer and kernel network stack. the difference is completely negligible. we are talking about 1us or less cheers luigi > > On Wed, Jun 5, 2013 at 8:45 AM, Luigi Rizzo <rizzo@iet.unipi.it> wrote: > > > On Tue, Jun 04, 2013 at 04:06:35PM -0500, Chao Xu wrote: > > > Hello, > > > > > > Is it possible to hacking some wireless NIC driver (carl9170 for example) > > > to enable netmap on it? I guess this is possible because wireless drivers > > > also manage packets using ring buffers. My goal is to access the raw > > > packets as quickly as possible, not to achieve high data rate. Is there > > any > > > argument against doing so? Thank you. > > > > as other said, there is no negative argument but it does not > > seem worthwhile, because at least with current packet rates > > you should be able to extract packets using pcap. > > Unless, of course, you are running a 300Mbit/s interface > > on a slow embedded CPU, in which case the efficiency of > > netmap might be helpful. > > > > cheers > > luigi > > > > > > -- > Regards, > Chao Xu
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