Limitations of gr_block: max_possible_items_available = 8191

GNU Radio
1

Hello,

I created a block with a variable input rate, but when I
run the flowgraph I get the following error:

sched: is requesting
more input data
than we can provide.
ninput_items_required = 16000

max_possible_items_available = 8191
If this is a filter, consider
reducing the number of taps.

If I don’t exceed the limit of 8191 items
the block works correctly but I need to exceed this limit for the
experiments I’m doing.

Is this a limitation of gr_block? Is there any
way to exceed this limit?

In the other way I tried to use
gr_sync_decimator but does not work because sometimes I need to consume
16000 ninput_items, sometimes 15999, and so on, and gr_sync_decimator
seems to have a fixed rate.

Thank you in advance. Best regards.

Luis

2

On Tue, Aug 14, 2012 at 12:52:11PM +0200, [email protected]
wrote:

If this is a filter, consider reducing the number of taps.

If I don’t exceed the limit of 8191 items the block works correctly but I need
to exceed this limit for the experiments I’m doing.

Is this a limitation of gr_block? Is there any way to exceed this limit?

I believe this is to do with the buffer limits between blocks (which are
set by the Linux kernel).

Do you really need this many input items per output item? If so, you
can also buffer manually, inside the block–here, there are no limits
other than the amount of RAM you have.

In the other way I tried to use gr_sync_decimator but does not work because
sometimes I need to consume 16000 ninput_items, sometimes 15999, and so on, and
gr_sync_decimator seems to have a fixed rate.

Yep, it’s fixed. Use a gr_block, and use set_relative_rate() to
1.0/16000 or whatever.

MB

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