Excessive over-allocation

[kvark]

A piece of log:

general.rs(613) 		Size 134217728, ready BitSet { mask: 1, groups: 1 }
general.rs(615) 			(0, Chunk { flavor: Dedicated { memory: Memory { raw: Memory { raw: 0xe278000000e278 }, size: 1073741824, properties: DEVICE_LOCAL, non_coherent_atom_size: None }, ptr: None }, blocks: 254 })

Use requested 128Mb, we allocated 1Gb.
Notably, in this run the max_chunk_size was selected to be 1/8th of available memory.
Also related to #24