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Re: [Discuss-gnuradio] Losing data somewhere between USRP and hard drive
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Losing data somewhere between USRP and hard drive |
Date: |
Sun, 12 Aug 2007 23:31:57 -0700 |
User-agent: |
Mutt/1.5.9i |
On Sun, Aug 12, 2007 at 06:10:21PM -0700, Chris Stankevitz wrote:
> Hello,
>
> Q1: If I use a file_sink to record data, and my app never reports "Ou"
> on the console, have all the bits been written to disk?
>
> Q2: Does anyone have a suggestion about how I can avoid Ou messages when
> using file_sink?
* If using ext3 file system, try remounting it as ext2.
* Buy a faster disk.
> Q1 commentary: Sometimes the data I get from file_sink looks funky. It
> could be a problem with my implementation of my application, but I
> suspect the data is corrupted and I suspect it contains gaps eventhough
> no "Ou" was reported.
No clue. usrp_rx_cfile.py is known to work ;)
> Q2 commentary: Ramdisk doesn't work because I'm writing gigabytes of
> data. I am thinking maybe I could write a multithreaded file_sink that
> operates more cleverly than the currently implementation. I am sampling
> 4e6 complex short samples per second.
What OS are you using?
What filesystem are you using?
Have you tried benchmarking your filesystem i/o throughput?
How about testing for any "pauses" where nothing else can get done.
E.g., posting the ext3 journal.
> I have also tried sending the data over TCPIP using
> file_descriptor_sink attached to a python socket with
> setblocking(0). Even when the receiving server is just throwing
> away the data (i.e. no disk access or processing) data is sometimes
> lost.
16MB/s * 8 bits/byte = 128Mbit/s
Are you using gigabit ethernet?
Eric