Enum Mamba3SsdPath 

pub enum Mamba3SsdPath {
    Minimal(Option<usize>),
    Serial(Option<usize>),
    SerialRecalculated(Option<usize>),
}

Algorithm selection for the Mamba-3 chunkwise SSD.

This selects the chunkwise SSD algorithm. The pathway (double- vs single-ssd) is selected separately, by the supplied cache variant (see crate::mamba3::cache::Mamba3Caches); Mamba3::forward threads this same selection into whichever pathway the cache implies, converting it into the per-pathway input bundle (crate::mamba3::double_ssd::ssd::Mamba3DoubleSsdInput or crate::mamba3::single_ssd::ssd::Mamba3SingleSsdInput) and calling that bundle’s run.

Each variant carries an optional chunk length. Larger values increase the intra-chunk GEMM work and reduce the inter-chunk scan length; the optimal value is approximately √(state_rank · per_head_dim) (see Self::optimal_chunk_len). None falls back to that optimal value.

If no path is specified, the cache defaults to crate::mamba3::cache::Mamba3Caches::SingleSsd with Self::default (i.e. Self::SerialRecalculated with an unset chunk length).

Variants

Minimal(Option<usize>)

Minimal/segsum SSD: mostly batched matmuls; backward via autodiff.

See crate::mamba3::double_ssd::ssd::Mamba3DoubleSsdInput::double_ssd_minimal / crate::mamba3::single_ssd::ssd::Mamba3SingleSsdInput::single_ssd_minimal. For training, prefer Self::SerialRecalculated.

Serial(Option<usize>)

(Hybrid) serial SSD: a serial loop over the chunks plus batched matmuls; backward via autodiff.

See crate::mamba3::double_ssd::ssd::Mamba3DoubleSsdInput::double_ssd_serial / crate::mamba3::single_ssd::ssd::Mamba3SingleSsdInput::single_ssd_serial. For a memory-saving custom backward, see Self::SerialRecalculated.

SerialRecalculated(Option<usize>)

(Hybrid) serial SSD with a custom, memory-efficient backward that recomputes the forward intermediates instead of storing them.

See crate::mamba3::double_ssd::ssd::Mamba3DoubleSsdInput::double_ssd_serial_recalculated / crate::mamba3::single_ssd::ssd::Mamba3SingleSsdInput::single_ssd_serial_recalculated. For a plain autodiff backward, see Self::Serial.

Implementations

impl Mamba3SsdPath

pub fn optimal_chunk_len(state_rank: usize, per_head_dim: usize) -> usize

Optimal chunk length, approximately √(state_rank · per_head_dim), rounded up to a multiple of 32 and capped at 512.

pub fn chunk_len(&self) -> Option<usize>

The chunk length carried by this variant, if any.

pub fn chunk_len_or_optimal( &self, state_rank: usize, per_head_dim: usize, ) -> usize

The chunk length carried by this variant, or Self::optimal_chunk_len when unset.

pub fn default_optimal_from_block(block: &Mamba3) -> Self

The recommended default path for a given block: Self::SerialRecalculated with Self::optimal_chunk_len for the block’s dimensions.

Trait Implementations

impl Clone for Mamba3SsdPath

fn clone(&self) -> Mamba3SsdPath

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Mamba3SsdPath

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Mamba3SsdPath

fn default() -> Self

Returns the “default value” for a type.