To help analyze the allocation of memory blocks by blist functions, add a method for analyzing the radix tree structures and reporting on the number, and sizes, of maximal intervals of free blocks. The report includes the number of maximal intervals, and also the number of them in each of several size ranges, from small (size 1, or 3 to 4) to large (28657 to 46367) with size boundaries defined by Fibonacci numbers. The report is written in the test tool with the 's' command, or in a running kernel by sysctl.