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From: | Juha Vierinen |
Subject: | Re: [Discuss-gnuradio] b210 overflows and huge usb buffer |
Date: | Mon, 12 Jan 2015 17:17:59 +0000 |
On 01/11/2015 10:38 PM, Marcus D. Leech wrote:
On 01/11/2015 10:26 PM, Juha Vierinen wrote:
Hi,
Now that the b210 timing issue now solved (thanks to Ian and Balint!),
I'm trying to get samples to disk at about 50 MHz. I have more than
I've streamed through programs like mbuffer before, to iron out an uneven disk recording rate. But I can't say I understand all of the GR and Linux buffering interaction well enough to be sure why it worked.
the required bandwidth on the disk, but there are occasional I/OThose limits are likely not imposed by UHD, per se, but by underlying
hiccups. With the N2x0 I just set the recv_buff_size to 1e9 and that
solves pretty much all the I/O hangups I get. With the b210 there
seems to be a driver imposed limit on the number of receive frames
however, which prevent me from increasing num_recv_frames above 2000.
At higher values, I get a uhd driver error and no samples come out of
the uhd source. How can I increase the usb buffers on the b210 to
about 1-2 GB? I don't care about latency, I just want to avoid long
gaps in the data that are caused by the disk occasionally hanging up.
I have tested the b210 with a null sink and there are no dropped packets.
I've tried everything to reduce disk hangups by changing the
filesystem cache settings with some limited help, but I still can't
completely remove occasional usb 3.0 packet drops. I'm convinced that
simply using a multi gigabyte buffer is the easy way out solution, but
I can't make this happen with the current uhd driver.
juha
libusb implementation details, and the drivers in the kernel that "feed"
libusb, and then
the hardware USB controllers.
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