Skip to content

perf.md

Latest commit

 

History

History
102 lines (76 loc) · 4.39 KB

perf.md

File metadata and controls

102 lines (76 loc) · 4.39 KB
Raw

Performance Tuning

AC fast-bitwise compile-time configuration

In the AC compression/decompression paths, there exist some compile-time configurations that can affect runtime performance varyingly depending on the usecase.

These are controlled crate-locally through crates/infotheory/build.rs with environment variables, so global RUSTFLAGS edits are not required.

# default:
#   encode: inline
#   decode: deinline
cargo build -p infotheory --release --features cli --bin infotheory --locked

# both de-inlined:
INFOTHEORY_AC_ENCODE_DEINLINE=1 \
cargo build -p infotheory --release --features cli --bin infotheory --locked

# both inlined:
INFOTHEORY_AC_DECODE_INLINE=1 \
cargo build -p infotheory --release --features cli --bin infotheory --locked

# custom combination (example for benchmarking):
INFOTHEORY_AC_ENCODE_DEINLINE=1 \
INFOTHEORY_AC_DECODE_INLINE=1 \
CARGO_INCREMENTAL=0 \
cargo build -p infotheory --release --features cli --bin infotheory --locked

AC fast-bitwise helper inlining matrix

The AC fast-bitwise encode/decode helper boundary is intentionally compile-time configurable. A local matrix benchmark was run on the two-json suite to compare the four layout variants against the default monolithic baseline.

Benchmark conditions:

  • Suite: two-json
  • Backend: rate-ac
  • Sizes: 4096 16384 65536 262144 1048576 2097152 4194304
  • Repeats: 3
  • Warmups: 0
  • Metric: mean of summed raw real_seconds per repeat
  • Output stability: all variants preserved archive bytes, entropy values, and verification status.

Variant meanings:

Variant Encode helper Decode helper
baseline original inline body original inline body
both-deinlined inline(never) inline(never)
comp-inlined inline(always) inline(never)
dec-inlined inline(never) inline(always)
both-inlined inline(always) inline(always)

Whole-matrix result:

Variant Mean total time Stdev Delta vs baseline
baseline 2136.093s 1.459s —
both-deinlined 2139.473s 1.223s +0.158%
comp-inlined 2135.147s 0.257s -0.044%
dec-inlined 2135.733s 2.072s -0.017%
both-inlined 2133.747s 1.427s -0.110%

Targeted effects:

Metric Baseline both-deinlined comp-inlined dec-inlined both-inlined
match decompress 4.347s 4.027s (-7.36%) 4.073s (-6.29%) 4.023s (-7.44%) 4.393s (+1.07%)
rwkv7 total 328.420s 330.987s (+0.78%) 329.157s (+0.22%) 330.503s (+0.63%) 327.790s (-0.19%)
rwkv7 compress+decompress 223.267s 224.713s (+0.65%) 223.503s (+0.11%) 224.173s (+0.41%) 222.637s (-0.28%)
neural_mixture total 1103.503s 1104.830s (+0.12%) 1104.813s (+0.12%) 1103.713s (+0.02%) 1102.653s (-0.08%)
ctw total 349.577s 349.140s (-0.12%) 348.550s (-0.29%) 348.843s (-0.21%) 348.923s (-0.19%)
non-match total 2126.863s 2130.570s (+0.17%) 2126.177s (-0.03%) 2126.827s (-0.00%) 2124.470s (-0.11%)

Chosen default:

Helper Default
encode fast-bitwise AC helper inline(always)
decode fast-bitwise AC helper inline(never)

This corresponds to the comp-inlined variant.

CTW research knobs

The FAC-CTW work on this branch selected hot-prefix depth 12 as the current default after a completed sweep. That tuning knob is still available for research builds through INFOTHEORY_CTW_HOT_PREFIX_DEPTH.

# default branch choice: hot-prefix depth 12
cargo build -p infotheory --release --features "cli backend-ctw" --bin infotheory --locked

# research override example
INFOTHEORY_CTW_HOT_PREFIX_DEPTH=10 \
cargo build -p infotheory --release --features "cli backend-ctw" --bin infotheory --locked

The ctw-profile CLI mode and the detailed FAC telemetry surface are treated as research-only tooling. They are intentionally excluded from more minimal CLI builds and require the research-tooling feature.

cargo build -p infotheory --release --features "cli backend-ctw research-tooling" --bin infotheory --locked

That split keeps the profiling path available for branch research while preserving a straightforward way to produce a leaner runtime binary when the extra tooling surface is not wanted.