[pvrusb2] hauppage hvr-1900 on raspberry pi

[Emmanuel Touzery]

Hello,

 Thanks for a lot for the tip. I tried quickly with a SMB share which I
already had setup and... yes it seems better! Although I really can't
believe it, it does seem to help. I'm glad you give me a plausible
explanation with DMA though, because that's the last thing I was expecting.
Especially since my network is not wired and though it's plugged using
ethernet on the pi, it reaches my computer through wifi.

 I'll try more. I didn't try much with USB keys too because I measured a
slightly lower throughput than with the SD card and I read that on the pi,
the throughput for USB+ethernet is shared. I figured, since USB is already
busy receiving the data from the video capture device, better save on the
SD... but apparently not.

 But really I can't conclude much until I test more. The first tests seems
to say network>usb>sd. but even on network I've seen a skip. Though it's on
a non-preempt kernel and without any sort of buffering (eg flywheel or
fifo), nor nice or chrt.

 Anyway, it seems there's not much hope of configuring something
differently on the driver or the kernel, so for now I'll focus on where to
save: SD, network, usb, with or without FIFO and so on. And maybe also NFS
vs SMB, if SMB doesn't always cut it. Definitely network appears the most
promessing option for now! So thanks again for the tip!

emmanuel

On Wed, Jun 6, 2012 at 10:27 PM, Felix Lighter <felix.lighter at gmail.com>wrote:

> Saving to a network share (e.g. NFS with intermediate block size)
> might perform better.
> The Ethernet port is likely to be much better served by the CPU's DMA
> facilities than its SD interface is.
>
> Cheers, FL
>