I'm glad that Ethernet helped the situation. Beware USB - it's also notorious for aggressively interrupting the CPU. 480Mbps USB2 comes at a high price, CPU-wise. And as you point out, it's already busy capturing video.
I would definitely suggest looking into NFS, since you should be able to lighten the CPU load even further by increasing the write buffer size (in the mount options). Take a look and see whether Samba also offers any options for tuning network usage / bandwidth. Cheers, FL On 7 June 2012 15:43, Emmanuel Touzery <[email protected]> wrote: > 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 <[email protected]>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 >> > _______________________________________________ > pvrusb2 mailing list > [email protected] > http://www.isely.net/cgi-bin/mailman/listinfo/pvrusb2 _______________________________________________ pvrusb2 mailing list [email protected] http://www.isely.net/cgi-bin/mailman/listinfo/pvrusb2
