Output of room in 32-bit LispWorks

Given an argument of nil, a summary of the total allocation in the entire heap (in kilobytes) is produced. The "allocated" figure only represents the amount of space allocated in heap segments that are writable, as opposed to read-only segments that hold some of the system code such as the garbage collector (GC) itself. The free space figure covers all the free space in all segments. To obtain these values programmatically, call room-values.

When called without an argument, room additionally prints information on the distribution of space between the generations of the heap.

When called with argument t, a breakdown of allocation in the individual segments of each generation is produced. Each segment is identified by its start address in memory. For each segment there is a free space threshold (the "minimum free space")--when the available space in the segment falls below this value, the GC takes action to attempt to free more space in this segment.

Two statistics about promotion are also reported on a per-segment basis: the number of sweeps that an object must survive in this generation before becoming eligible for promotion, and the total volume of objects that have survived for that long and are consequently awaiting promotion to the next generation. These statistics are not relevant for static segments, which are indicated as "static".

room prints numbers in decimal format, except for the segment start addresses which it prints in hexadecimal format.

Output of room in 64-bit LispWorks

The last line of the output of room is always a line containing the total allocated amount (memory occupied by live objects) and the total size (memory that LispWorks has allocated from the OS) (the "total line"). Both numbers are given in decimal followed parenthetically by the same number in hexadecimal. Above the total line is information for each generation.

(room nil) does not print any information about generations.

(room) prints the amount allocated for each generation in decimal.

(room :full) prints for each generation the amount allocated, both in decimal and in hexadecimal, and then the allocated amount of each allocation type in which there is any allocation in this generation.

(room t) prints for each generation the same as (room :full), followed by information about the segments in this generation. For each segment it prints the allocation type and the start and end address for allocation in this segment.

Note that information for segments does not correspond to the allocated size, because not all the area in the segment is currently allocated.

See Memory Management in 64-bit LispWorks for a description of allocation types and segments.

Output of room in the Mobile GC

The last line of the output of room is always a line containing the total allocated amount (memory occupied by live objects) and the total size (memory that LispWorks has allocated from the OS) (the "total line"). Both numbers are given in decimal followed parenthetically by the same number in hexadecimal. Above the total line is information for each generation.

(room) and (room :default) prints the allocated and free sizes according to these types:

Cons

cons object only.

Other

All other objects, except static objects and large objects (> 1 MB).

Static

Static objects.

Large

Large objects (> 1 MB). Note: this threshold may change in the future, but it is fixed in the current version.

The Cons and Other segments are divided according to their generation and there may also some permanent segments (as a result of a call to make-current-allocation-permanent, make-object-permanent or make-permanent-simple-vector).

In addition, LispWorks also holds some reserved segments that are used during GC, and room prints the size of these too.

(room t) also prints the segments for each type. For each segment, it prints the start and end addresses (in hex), the allocated area, and whether there is a free "hole" in the middle of it. For the Large and Static segments, it also prints the generation number of each segment. Permanent Static and Large segments have generation number 3.

See Mobile GC technical details for more technical details.