The three columns show, respectively, total time, user time, and system time. "Main promote" indicates promotions from generation 0. "Internal promote" indicates when an attempt to promote from one generation to the next causes promotion of the higher generation, to make room for the objects from the lower generation. "fixup" is a part of the compaction and promotion process.
USER 22 > (hcl:extended-time (hcl:clean-generation-0))
user time = 1.320
system time = 0.100
Elapsed time = 0:00:01
Allocation = 144
0 Page faults
total gc activity = 0.960000 / 0.900000 / 0.060000
main promote (0 calls) = 0.000000 / 0.000000 / 0.000000
mark and sweep (200 calls) = 0.960000 / 0.900000 / 0.060000
internal promote ( 100 calls = 0.000000 / 0.000000 / 0.000000
promote ( 0 calls) = 0.000000 / 0.000000 / 0.000000
fixup ( 100 calls) = 0.140000 / 0.120000 / 0.020000
compact ( 0 calls) = 0.000000 / 0.000000 / 0.000000
NIL
USER 23 >