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gc: Moved incremental gc behind ifdef LFS_GC

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Incremental gc, being stateful and not gc-able (ironic), was always
going to need to be conditionally compilable.

This moves incremental gc behind the LFS_GC define, so that we can focus
on the "default" costs. This cuts lfs_t in nearly half!

  lfs_t with LFS_GC:   308
  lfs_t without LFS_C: 168 (-45.5%)

This does save less code than one might expect though. We still need
most of the internal traversal/gc logic for things like block allocation
and orphan cleanup, so most of the savings is limited to the RAM storing
the incremental state:

                          code          stack          ctx
  before:                37916           2608          768
  after with LFS_CFG:    37944 (+0.1%)   2608 (+0.0%)  768 (+0.0%)
  after without LFS_CFG: 37796 (-0.3%)   2608 (+0.0%)  620 (-19.3%)

On the flip side, this does mean most of the incremental gc
functionality is still availables in the lfsr_traversal_t APIs.

Applications with more advanced gc use-cases may actually benefit from
_not_ enabling the incremental gc APIs, and instead use the
lfsr_traversal_t APIs directly.
This commit is contained in:
Christopher Haster
2025-01-06 20:34:40 -06:00
parent 5d756fe698
commit 1b3054db89
8 changed files with 220 additions and 125 deletions
Download Patch File Download Diff File Expand all files Collapse all files
runners/bench_runner.h
+9 -2
View File
@@ -145,14 +145,21 @@ void bench_permutation(size_t i, uint32_t *buffer, size_t size);
.pcache_size = PCACHE_SIZE, \
.file_buffer_size = FILE_BUFFER_SIZE, \
.lookahead_size = LOOKAHEAD_SIZE, \
.gc_flags = GC_FLAGS, \
.gc_steps = GC_STEPS, \
BENCH_GC_CFG \
.gc_compact_thresh = GC_COMPACT_THRESH, \
.inline_size = INLINE_SIZE, \
.shrub_size = SHRUB_SIZE, \
.fragment_size = FRAGMENT_SIZE, \
.crystal_thresh = CRYSTAL_THRESH,
#ifdef LFS_GC
#define BENCH_GC_CFG \
.gc_flags = GC_FLAGS, \
.gc_steps = GC_STEPS,
#else
#define BENCH_GC_CFG
#endif
#define BENCH_BDCFG \
.erase_value = ERASE_VALUE, \
.erase_cycles = ERASE_CYCLES, \
runners/test_runner.h
+10 -3
View File
@@ -136,13 +136,20 @@ void test_permutation(size_t i, uint32_t *buffer, size_t size);
.pcache_size = PCACHE_SIZE, \
.file_buffer_size = FILE_BUFFER_SIZE, \
.lookahead_size = LOOKAHEAD_SIZE, \
.gc_flags = GC_FLAGS, \
.gc_steps = GC_STEPS, \
TEST_GC_CFG \
.gc_compact_thresh = GC_COMPACT_THRESH, \
.inline_size = INLINE_SIZE, \
.shrub_size = SHRUB_SIZE, \
.fragment_size = FRAGMENT_SIZE, \
.crystal_thresh = CRYSTAL_THRESH,
.crystal_thresh = CRYSTAL_THRESH
#ifdef LFS_GC
#define TEST_GC_CFG \
.gc_flags = GC_FLAGS, \
.gc_steps = GC_STEPS,
#else
#define TEST_GC_CFG
#endif
#define TEST_BDCFG \
.erase_value = ERASE_VALUE, \