[Discuss-gnuradio] What factor determines input_item size (ninput_items)?

I am testing my OOT module in various condition of different machines.

A certain block implementing a state machine requires a certain number of items or more.

Thus, I've stated it in forecast():
https://gist.github.com/gsongsong/9ba1cb974a57a0861678#file-forecast-my_block-cpp

In general work(), the block determines how many items it should be consume:
https://gist.github.com/gsongsong/9ba1cb974a57a0861678#file-general_work-my_block-cpp

With these codes, it works find with my own machinie.

Ubuntu 14.04, 2 CPUs and 4 GB RAM allocated virtual machine. The host has i7-3770 and 16 GB RAM.

But it fails on machine that my school gave to me for educational and research purposes. I can't tell you the exact spec. of the machine, but it apparently has a poor CPU and a lower memory space.

Do these difference on machines' specs affect on ninput_items? I think they have a certain relation to each other... since GNU Radio scheduler allocates available memory over all blocks...? If so, can it be resolved if I manually set a larger memory/buffer size to GNU Radio? (If my memory is correct, I remember there's a configuration file to do it...)

Regards,

Jeon.