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Limited FRAGMENT_SIZE to 512 bytes in the test/bench runners

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This prevents runaway O(n^2) behavior on devices with extremely large
block sizes (NAND, bs=~128KiB - ~1MiB).

The whole point of shrubs is to avoid this O(n^2) runaway when inline
files become necessarily large. Setting FRAGMENT_SIZE to a factor of the
BLOCK_SIZE humorously defeats this.

The 512 byte cutoff is somewhat arbitrary, it's the natural BLOCK_SIZE/8
FRAGMENT_SIZE on most NOR flash (bs=4096), but it's probably worth
tuning based on actual device performance.
This commit is contained in:
Christopher Haster
2025-05-15 17:18:51 -05:00
parent 275ca0e0ec
commit bf00c4d427
2 changed files with 2 additions and 2 deletions
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runners/bench_runner.h
+1 -1
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@@ -118,7 +118,7 @@ void bench_permutation(size_t i, uint32_t *buffer, size_t size);
BENCH_DEFINE(GC_STEPS, 0 ) \
BENCH_DEFINE(GC_COMPACT_THRESH, 0 ) \
BENCH_DEFINE(INLINE_SIZE, BLOCK_SIZE/4 ) \
BENCH_DEFINE(FRAGMENT_SIZE, BLOCK_SIZE/8 ) \
BENCH_DEFINE(FRAGMENT_SIZE, LFS_MIN(BLOCK_SIZE/8, 512) ) \
BENCH_DEFINE(CRYSTAL_THRESH, BLOCK_SIZE/8 ) \
BENCH_DEFINE(FRAGMENT_THRESH, -1 ) \
BENCH_DEFINE(ERASE_VALUE, 0xff ) \