- the collector now promotes objects one generation higher at a time
by default. previously, it promoted every live oldspace object to
the selected target generation, which could result in objects
prematurely skipping one or more generations and thus being
retained longer than their ages justify. the biggest cost in
terms of code complexity and performance is the recording of
pointers from older newspace objects to younger newspace objects
that could not previously occur.
gc.c, alloc.c, externs.h
- the collect procedure now takes an additional optional minimum
target generation argument to allow the new default behavior to
be overridden.
7.ss, primdata.ss,
gcwrapper.c,
7.ms, root-experr*,
smgmt.stex, release_notes.stex
- added cn flag to control collect-notify
mats/Mf-base
- resweep_weak_pairs now sets sweep_loc to orig_next_loc rather than
first_loc since the latter could result in unnecessary sweeping of
existing target-generation weak pairs.
gc.c
- added set of S_child_processes[newg] to S_child_processes[oldg]
in S_do_gc code handling decreases in the maximum generation.
gcwrapper.c
- a specialized variant of the collector is used in the common case
where the max copied generation is 0, the min and max target
generations are 1, and there are no locked generation 0 objects
is now used. with the default collection parameters and no locking
of generation 0 objects, these collections account for 3/4 of all
collections.
gc.c, gc-011.c (new), gcwrapper.c, externs.h, c/Mf-base
- maybe-fire-collector no longer tries to be so precise and instead
just counts the number of generation-bytes allocated since the
last gc. suprisingly, rebuilding the s directory requires about
the same number of collections with this coarser (and less
expensive) measurement. this change also fixes a problem with
too-frequent collections when the maximum-generation is set to
zero. to make the determination even less expensive, a running
total of bytes in each generation is now maintained in a new
bytes_of_generation vector, and maybe-fire-collector is no longer
called when the collector is running.
alloc.c, gc.c, gcwrapper.c, globals.h
- copy now copies two pairs at once only if they are in the same
segment, which saves a few memonry references and tests and turns
out not to reduce the number of opportunities significantly in
tested programs.
gc.c
- occupied_segments, first_loc, base_loc, next_loc, bytes_left,
bytes_of_space, sweep_loc, and orig_next_loc are now indexed
by [g][s] rather than [s][g] to improve locality in the default
(and common) case where there are only a handful of active
generations.
globals.h, types.h, segment.c, gc.c, gcwrapper.c, prim5.c
- now maintaining 16-byte architectural stack alignment (if the
incoming stack is so aligned) on all x86 platforms except
i3nt/ti3nt. more recent versions of gcc sometimes generate sse
instructions that require 16-byte stack alignment.
x86.ss
[Merge for Racket includes additional changes to combine with in-place
marking - mflatt]
48487ed6fb