Re: [Discuss-gnuradio] Memory issues

[bob wole]

Marcus,

Certainly a type. Since Maricus did not mention any hardware sink I was just reminding him to add a throttle block if it is not there :)

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Bob

On Thu, Jul 30, 2015 at 11:13 AM, Marcus Müller <address@hidden> wrote:

Hi Bob,

Sorry I have to contradict here: when working with hardware, you should generally *never* use a throttle block. Maybe that was just a typo in your mail?

The reason is that the throttle blocks sole job is to call sleep functions for long enough to press the average rate of samples going through the throttle block is the set rate. Now, in a world where latency doesn't count and all clocks are identical, that's not a problem. However, in practice, this means that throttle might block for a relatively long time, when the numbers of samples it got in one work iteration are large. In the meantime, the downstream hardware might have run dry on samples, even if the throttle rate is higher than the sink's sampling rate!

Also, with rates produced by your computer's clock and the oscillator of a hardware sink, one has to be a little faster than the other, which leads to under or overflow problems sooner or later.

However, in the pure simulation case, I agree, you should add a throttle and see whether it helps.

Best regards,
Marcus

Am 30. Juli 2015 07:10:13 MESZ, schrieb bob wole <address@hidden>:

Maricus,

Does your flowgraph involves aany hardware sink e.g USRP, audio ? If try adding a throttle if you are not already doing it.

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Bob

Hi Marius,

good question!
Now, typically, you'd use tools like valgrind to figure that out. I
haven't noticed a memory leak in GNU Radio itself, but it's absolutely
possible that something like PMTs do not get freed etc, and we didn't
notice how this could happen.
If you need additional things to look for:
* do you have something like a vector that stores e.g. messages that
come in?
* what's the failure mode of your application? Is it killed by the
Out-of-Memory killer, or do you get into a situation where it crashes
because of e.g. stack overflow?

Best regards,
Marcus

On 29.07.2015 15:57, Marius Cachelin wrote:
> Hi all,
>
> I am writing because I have some misunderstood concerning how memory
> is used in GNURadio.
>
> I developed a transmitter which can be split into 5 parts :
>    - MAC Encoder : read PDU data from TUNTAP
>    - HEADER Prefixer : add header before each PDU Data
>    - PREAMBLE prefixer : add preamble before each PDU Data
>    - MODULATOR : Performing BPSK/QPSK
>    - FIR Interp : Pulse shape
>
> My question is : when I run my transmitter, I can see in HTOP that the
> memory (%MEM) used by my transmitter increase. The increasing is
> relatively slow, but the is an issue because I can't keep using my
> transmitter after a while.
>
> I have checked all my blocks. All memory allocations are freed, and
> all my objetcs (new...) are deleted.
>
> So, how the memory can increase if I do not allocate extra memory and
> free all memory?
>
> Thanks you in advance.
>
> --
> *CACHELIN Marius*
> /Ing?nieur Syst?mes, R?seaux et T?l?communications/
> address@hidden <mailto:address@hidden

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