Re: [Discuss-gnuradio] Strange output of "0" at the terminal

[mleech]

Modern disk subsystems can easily sustain 80MB or more per second even on relativley wimpy hardware

What is the sample rate involved here?  Seriously, I've been able to stream multi-MHz of bandwidth to disk for long periods without any 'O' happening.

-Marcus

On Fri, 24 Feb 2012 11:23:05 -0500, Andrew Davis wrote:

> You are writing to a file in a blocking thread, its not the CPU it's
> the hard drive. You should try the program without the write. Then if
> it is the problem you should write out to a file on a ram disk then
> save it to a real disk later.
>
> 2012/2/24 Wu Ting <address@hidden>:
> > Hi! Thank you for your suggestions!
> >
> > I realized it is a problem related with computer speed. Today I used a
> > laptop to run the same code, and 'O' is printed much more frequently.
> >
> > However, the computer I'm using is a quite good one. It has intel i7
> > 3.4GHz 8-core, and when the code is running, CPU is only used by about
> > 10%, and memory is also used by no more than 15%. On the other hand, I
> > also checked number of messages in message queue, and I've found that when
> > 'O' is printed, sometimes there are only several messages in the queue. So
> > I don't understand why it has this outflow problem.
> >
> > And is it possible to catch this error when it happens, so that I can deal
> > with it in the problem?
> >
> > Thanks!
> >
> > Wu
> >
> > > 2012/2/23 Wu Ting <address@hidden>
> > >
> > > > Hi! Thank you for your response. I've kept working on this problem for
> > > > two
> > > > days, but still cannot find a way to solve it.
> > > >
> > > > I simplified the program and have determined that the 'O' is produced is
> > > > this while loop:
> > > >
> > > > while msgCount<10000:
> > > >    msg = tb.queue.delete_head()
> > > >    payload = msg.to_string()
> > > >    f.write(payload)
> > > >    msgCount += 1
> > > >
> > > > I also tried to make it sleep for a short time after each operation:
> > > >
> > > > while msgCount<10000:
> > > >    msg = tb.queue.delete_head()
> > > >    sleep(0.00001)
> > > >    payload = msg.to_string()
> > > >    sleep(0.00001)
> > > >    f.write(payload)
> > > >    sleep(0.00001)
> > > >    msgCount += 1
> > > Two quick things. First, the tb.queue.delete_head() is a blocking call, so
> > > it will wait until there is a message to process. You don't need to sleep.
> > > Adding a sleep call here is probably only making things worse since you're
> > > already not keeping up with the samples. Second, the sleep() call is
> > > generally only accurate to about ~10 ms, but you're asking it to sleep for
> > > 10 us. I'm not sure if it rounds up or down. Worse case, you're making the
> > > loop sleep for about 30 ms total; best case is you actually aren't pausing
> > > at all.
> > >
> > > Tom
>
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