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Added BENCH/TEST_PRNG, replacing other ad-hoc sources of randomness

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When you add a function to every benchmark suite, you know if should
probably be provided by the benchmark runner itself. That being said,
randomness in tests/benchmarks is a bit tricky because it needs to be
strictly controlled and reproducible.

No global state is used, allowing tests/benches to maintain multiple
randomness stream which can be useful for checking results during a run.

There's an argument for having global prng state in that the prng could
be preserved across power-loss, but I have yet to see a use for this,
and it would add a significant requirement to any future test/bench runner.
This commit is contained in:
Christopher Haster
2022-11-30 11:23:04 -06:00
parent d8e7ffb7fd
commit b0382fa891
10 changed files with 134 additions and 124 deletions
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benches/bench_file.toml
+5 -19
View File
@@ -1,17 +1,3 @@
# deterministic prng
code = '''
static uint32_t xorshift32(uint32_t *state) {
uint32_t x = *state;
x ^= x << 13;
x ^= x >> 17;
x ^= x << 5;
*state = x;
return x;
}
'''
[cases.bench_file_read]
# 0 = in-order
# 1 = reversed-order
@@ -33,7 +19,7 @@ code = '''
for (lfs_size_t i = 0; i < chunks; i++) {
uint32_t chunk_prng = i;
for (lfs_size_t j = 0; j < CHUNK_SIZE; j++) {
buffer[j] = xorshift32(&chunk_prng);
buffer[j] = BENCH_PRNG(&chunk_prng);
}
lfs_file_write(&lfs, &file, buffer, CHUNK_SIZE) => CHUNK_SIZE;
@@ -50,14 +36,14 @@ code = '''
lfs_off_t i_
= (ORDER == 0) ? i
: (ORDER == 1) ? (chunks-1-i)
: xorshift32(&prng) % chunks;
: BENCH_PRNG(&prng) % chunks;
lfs_file_seek(&lfs, &file, i_*CHUNK_SIZE, LFS_SEEK_SET)
=> i_*CHUNK_SIZE;
lfs_file_read(&lfs, &file, buffer, CHUNK_SIZE) => CHUNK_SIZE;
uint32_t chunk_prng = i_;
for (lfs_size_t j = 0; j < CHUNK_SIZE; j++) {
assert(buffer[j] == xorshift32(&chunk_prng));
assert(buffer[j] == BENCH_PRNG(&chunk_prng));
}
}
@@ -91,10 +77,10 @@ code = '''
lfs_off_t i_
= (ORDER == 0) ? i
: (ORDER == 1) ? (chunks-1-i)
: xorshift32(&prng) % chunks;
: BENCH_PRNG(&prng) % chunks;
uint32_t chunk_prng = i_;
for (lfs_size_t j = 0; j < CHUNK_SIZE; j++) {
buffer[j] = xorshift32(&chunk_prng);
buffer[j] = BENCH_PRNG(&chunk_prng);
}
lfs_file_seek(&lfs, &file, i_*CHUNK_SIZE, LFS_SEEK_SET)