Zero copy data transfer from Linuxulator to FreeBSD?

[Lundberg, Johannes]

Hi Luigi

Since this is an embedded device running on battery every bit counts.
However, this is kind of a temporary solution so I'm considering accepting
it..

At any rate, I am generally curious what mechanism there are for
transferring data between Linux and native process in FreeBSD..


On Fri, Apr 1, 2016 at 8:10 AM, Luigi Rizzo <rizzo at iet.unipi.it> wrote:

>
>
> On Fri, Apr 1, 2016 at 5:02 PM, Lundberg, Johannes <
> johannes at brilliantservice.co.jp> wrote:
>
>> Well, I did something similar a couple of years ago where I grab raw data
>> from a special infrared camera with proprietary USB driver. I sent the raw
>> data to a FreeBSD process using sockets where it is processed and becomes
>> the input data for the gesture recognition software API. It was kind of
>> unstable due to poorly written proprietary driver so I couldn't use it
>> that
>> much.
>>
>> Now there's a new device with totally new driver and I thought I'd give it
>> a try again. From my previous attempts I think I came to the conclusion
>> that shm can not be used between a Linux and a native process...
>>
>> Raw data transfer rate is something like 100 Mbit/sec (2.4 Mbit at 45
>> fps).
>>
>> I think the driver allocates memory for the data and transfers it there
>> from the USB device so I guess zero copy would be impossible.. At least if
>> I could do it with one copy would be nice..
>>
>
>
> ​With those low data rates the number of copies is completely
> irrelevant​
>
> ​on modern hardware. Save yourself the trouble of
> unnecessary optimizations and just privilege simplicity.
>
> cheers
> luigi
>
>
>> Something like:
>>
>> USB device -> Linux driver's memory -> [IPC] -> native process
>>
>>
>> On Fri, Apr 1, 2016 at 1:17 AM, Hans Petter Selasky <hp at selasky.org>
>> wrote:
>>
>> > On 04/01/16 04:38, Lundberg, Johannes wrote:
>> >
>> >> Hi
>> >>
>> >> I have a USB driver that runs in Linux mode and I want to transfer
>> data to
>> >> a native program for processing.
>> >>
>> >> I think that shared memory is not possible, what are other (zero copy)
>> >> options?
>> >>
>> >> Thanks!
>> >>
>> >>
>> > Can you explain a bit how the current program moves data around?
>> >
>> > --HPS
>> >
>>
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>
>
>
> --
> -----------------------------------------+-------------------------------
>  Prof. Luigi RIZZO, rizzo at iet.unipi.it  . Dip. di Ing. dell'Informazione
>  http://www.iet.unipi.it/~luigi/        . Universita` di Pisa
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CONFIDENTIALITY NOTE: The information in this email is confidential
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Disclosure, copying, distribution or any other action of use of this
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If you are not the intended recipient and have received this email in
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