Re: How to avoid scheduler error running out of memory to allocate

[Armin Ghani]

Thanks Jeff for your reply.

Yes, I just changed the values again right now but nothing changed. I set minoutbuf value from 1 to 10000 increasing 10 times more each time.

I dont know exactly why you suggested minoutbuf to be changed because what I understand is that block ofdm_serializer_vcc needs amount of input which is more than what shceduler can supply. Since number of input needed comes from number of output items to be produced, I dont get why minoutbuf is needed to be changed. If we want to make change to have lesser number of input items needed so we need to limit maxoutbuf instead. That makes more sense.

On 16/9/21 12:22, Jeff Long wrote:

Have you tried changing the minimum output buffer on either the block or the one before it? This can be done in the block parameters under the advanced tab. There is no reason to redefine GR_FIXED_BUFFER_SIZE, just change it where necessary. Buffers are on the output of each block.

On Thu, Sep 16, 2021 at 5:44 AM Armin Ghani <aghani@cttc.es> wrote:

Dear community

I've been tackling to fix below scheduler error which it fails to allocate buffer for blocks:

ched: <block ofdm_serializer_vcc (22)> is requesting more input data
  than we can provide.
  ninput_items_required = 960
  max_possible_items_available = 127
  If this is a filter, consider reducing the number of taps.

I'm curious to know how to mitigate such error. This issue has been covered very few but one of the workaround would be to change GR_FIXED_BUFFER_SIZE as much as the error disappears but this is not a good solution since it leads to scheduler sample propagation delays. I welcome every effective and reliable solution despite of being difficult to implement and etc.

Below there are a few solutions that came to my mind but none of them are final solutions:

- Trying to change GR_FIXED_BUFFER_SIZE. This leads to path delays which prevents flow graph to run smoothly

- Trying to remove extra blocks. This is not so effective

- Simplifying block implementation specially those which are implemented in hier-block approach by writing c++ code instead. This is also not so effective

- dividing top-block into smaller top-blocks with fever blocks. Not helpful

I'll be more than happy to hear you back.

Regards.

--

Armin Ghani

Research Engineer | Communication Systems Division (CSD)

aghani@cttc.es | +34 93 645 29 08 (2143)

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)

Av. Carl Friedrich Gauss, 7 - Edifici B4 - PMT

08860 - Castelldefels (Barcelona, Spain)

www.cttc.cat

--

Armin Ghani

Research Engineer | Communication Systems Division (CSD)

aghani@cttc.es | +34 93 645 29 08 (2143)

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)

Av. Carl Friedrich Gauss, 7 - Edifici B4 - PMT

08860 - Castelldefels (Barcelona, Spain)

www.cttc.cat