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Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink
From: |
Murphy, John |
Subject: |
Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink |
Date: |
Thu, 7 May 2015 14:57:52 -0400 |
Hi Marcus,
I am using num_recv_frames=512 but I have no idea why 512 or what the
ideal value should be for a system that has a lion's share of 16 GB of
RAM to burn.
In terms of the disk hardware sequential writes are up to 520
MBytes/sec. While there may still be some moments where things fall
behind, I expect some buffer somewhere, if properly set up (which I
believe is the issue but I do not know where or how), to be able to
take up the slack and prevent overruns.
Surely there must be poeple that do this all the time without O's,
given a proper setup?
- John
On Thu, May 7, 2015 at 2:27 PM, <address@hidden> wrote:
> Leave "unbuffered" = OFF. This flag was added for "slow" file-sinks, when,
> for example, you're writing slow data to an external process via somehthing
> like FIFO, and you don't want the default stdio buffering to get in the way.
> The default, if you leave it off, is to use stdio buffering.
>
> The "bursts of O" behaviour is to be expected, depending on how much RAM the
> kernel allocates to write-behind buffers, and how fast your disk subsystem
> is. Your writes get posted to the kernel. The kernel throws them into a
> usually-immense, write-behind cache. When its I/O scheduler decides its
> time to commit those writes, things slow down.
>
> You might try also using num_recv_frames on the device arguments (if you
> aren't already), to try and smooth out the flow from the USB controller.
>
> You might also compare what you're doing with something that doesn't use Gnu
> Radio at all, such as rx_samples_to_file.
- [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, mleech, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, mleech, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, mleech, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink,
Murphy, John <=
- Message not available
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, mleech, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Marcus D. Leech, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/09
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Marcus D. Leech, 2015/05/10
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/11
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/13
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/07
- Re: [Discuss-gnuradio] UHD USRP Source for B2x0 overflows File Sink, Murphy, John, 2015/05/07