Panic in subgroup_fft_in_place benchmark

[daira]

$ cargo +nightly bench
[...]
Benchmarking "mnt6_753 - mixed radix" - subgroup_fft_in_place/1048576: Warming up for 3.0000 sthread 'main' panicked at 'called `Option::unwrap()` on a `None` value', poly-benches/benches/fft.rs:43:33
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: bench failed

This was on the add-biginterger-into-from-biguint branch; not sure if that's relevant. I will try later to see if I can reproduce this with a backtrace and on master.

[daira]

This is reproducible on master:

daira@katava:~/research/algebra/poly-benches$ git rev-parse HEAD
ebd1c3f14a46f2a9992727d5ef51cf9ca963fb97
daira@katava:~/research/algebra/poly-benches$ RUST_BACKTRACE=full cargo +nightly bench 'subgroup_fft_in_place/1048576'
    Finished bench [optimized] target(s) in 0.05s
     Running /home/daira/research/algebra/target/release/deps/dense_multilinear-f05f1341652c05a9
WARNING: HTML report generation will become a non-default optional feature in Criterion.rs 0.4.0.
This feature is being moved to cargo-criterion (https://github.com/bheisler/cargo-criterion) and will be optional in a future version of Criterion.rs. To silence this warning, either switch to cargo-criterion or enable the 'html_reports' feature in your Cargo.toml.

     Running /home/daira/research/algebra/target/release/deps/dense_uv_polynomial-44cf4355ca5d175a
WARNING: HTML report generation will become a non-default optional feature in Criterion.rs 0.4.0.
This feature is being moved to cargo-criterion (https://github.com/bheisler/cargo-criterion) and will be optional in a future version of Criterion.rs. To silence this warning, either switch to cargo-criterion or enable the 'html_reports' feature in your Cargo.toml.

     Running /home/daira/research/algebra/target/release/deps/fft-a2ece2d48720aaf1
WARNING: HTML report generation will become a non-default optional feature in Criterion.rs 0.4.0.
This feature is being moved to cargo-criterion (https://github.com/bheisler/cargo-criterion) and will be optional in a future version of Criterion.rs. To silence this warning, either switch to cargo-criterion or enable the 'html_reports' feature in your Cargo.toml.

Benchmarking "bls12_381 - radix2" - subgroup_fft_in_place/1048576: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 56.1s, or reduce sample count to 10.
"bls12_381 - radix2" - subgroup_fft_in_place/1048576                                                                            
                        time:   [550.66 ms 551.61 ms 552.74 ms]
                        change: [-2.1659% -1.9715% -1.7114%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 4 outliers among 100 measurements (4.00%)
  3 (3.00%) high mild
  1 (1.00%) high severe

Benchmarking "mnt6_753 - mixed radix" - subgroup_fft_in_place/1048576: Warming up for 3.0000 sthread 'main' panicked at 'called `Option::unwrap()` on a `None` value', poly-benches/benches/fft.rs:43:33
stack backtrace:
   0:     0x55674bd09f31 - std::backtrace_rs::backtrace::libunwind::trace::hb4de9797f80b7b8c
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:     0x55674bd09f31 - std::backtrace_rs::backtrace::trace_unsynchronized::h59566d0bd20efff7
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x55674bd09f31 - std::sys_common::backtrace::_print_fmt::hcfa5ce6be50275d4
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x55674bd09f31 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd8c307a38b9bab04
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x55674bbabe7c - core::fmt::write::h3868db8542c90941
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/core/src/fmt/mod.rs:1092:17
   5:     0x55674bd04e52 - std::io::Write::write_fmt::hab90295d5a0f197d
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/io/mod.rs:1568:15
   6:     0x55674bd0bba5 - std::sys_common::backtrace::_print::h19224910b8700cf1
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x55674bd0bba5 - std::sys_common::backtrace::print::h25dedfa68c5fb84a
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x55674bd0bba5 - std::panicking::default_hook::{{closure}}::h12c5765653a72a42
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:208:50
   9:     0x55674bd0c5c1 - std::panicking::default_hook::he65cee71c4209f0c
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:225:9
  10:     0x55674bd0c5c1 - std::panicking::rust_panic_with_hook::h01a674d863fe0d8a
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:591:17
  11:     0x55674bd0bdbe - std::panicking::begin_panic_handler::{{closure}}::h9b9fecf185178864
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:495:13
  12:     0x55674bd0a5ac - std::sys_common::backtrace::__rust_end_short_backtrace::h57be46a42dc7f24b
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/sys_common/backtrace.rs:141:18
  13:     0x55674bd0bd5d - rust_begin_unwind
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:493:5
  14:     0x55674bbaa771 - core::panicking::panic_fmt::h20225113c4a2f8fd
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/core/src/panicking.rs:92:14
  15:     0x55674bbaa6bd - core::panicking::panic::h35b77276aa4b0c12
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/core/src/panicking.rs:50:5
  16:     0x55674bb2aca0 - fft::fft_common_setup::h49f1cd2bc295e71d
  17:     0x55674bb2ad8f - fft::bench_fft_in_place::habe6d95ccfed1e0a
  18:     0x55674bb34ae7 - <criterion::routine::Function<M,F,T> as criterion::routine::Routine<M,T>>::warm_up::h160df70a7595e4bf
  19:     0x55674bb34f3e - criterion::routine::Routine::sample::heae47f72909b8536
  20:     0x55674bb4bb6c - criterion::analysis::common::h5fa265362077573f
  21:     0x55674bb407b5 - criterion::benchmark_group::BenchmarkGroup<M>::bench_with_input::h73e08d1cb5335dd0
  22:     0x55674bc90950 - fft::setup_bench::h8f9c51cf5671ea12
  23:     0x55674bb2b569 - fft::fft_benches::hae5473918f4490d4
  24:     0x55674bc90a4f - fft::main::h41dbcd916ce7d852
  25:     0x55674bb177d6 - std::sys_common::backtrace::__rust_begin_short_backtrace::h37b0da6974e60185
  26:     0x55674bb1f80c - std::rt::lang_start::{{closure}}::h385306b3b4228dbe
  27:     0x55674bd0cc03 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::h2c4fd7d4128112a8
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/core/src/ops/function.rs:259:13
  28:     0x55674bd0cc03 - std::panicking::try::do_call::h41fb7dbbbe7bece6
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:379:40
  29:     0x55674bd0cc03 - std::panicking::try::hd38008ccba72bce1
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panicking.rs:343:19
  30:     0x55674bd0cc03 - std::panic::catch_unwind::h057e765cd60f2d13
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/panic.rs:431:14
  31:     0x55674bd0cc03 - std::rt::lang_start_internal::hdb9d0b9d2cdcda8b
                               at /rustc/3e826bb11228508fbe749e594038d6727208aa94/library/std/src/rt.rs:51:25
  32:     0x55674bc90b85 - main
  33:     0x7fad67204e0b - __libc_start_main
  34:     0x55674bb160aa - _start
  35:                0x0 - <unknown>

error: bench failed

[Pratyush]

Hmm, let me try to reproduce this. Thanks for the heads up!

[weikengchen]

Found the reason.

The bench program considers degrees of 2^15 to 2^22.

This is okay for BLS12-381::Fr, but not good for MNT6-753::Fr

use ark_test_curves::mnt4_753::Fq as mnt6_753_fr;

algebra/poly-benches/benches/fft.rs

Line 8 in e7eeea3

use ark_test_curves::mnt4_753::Fq as mnt6_753_fr;

The latter only has 2^15 * 5^2, which is smaller than 1048576, aka 2^20.

We can separate the benchmark size of the two curves, by separating the default_size_range for each curve.

[weikengchen]

A PR is on the way.