Enum RowXformKind 

pub enum RowXformKind {
    Rsqrt {
        eps_nano: u64,
        over: usize,
    },
}

How a reduced per-row scalar becomes the multiplier the rescale broadcasts back across the row.

Variants

Rsqrt

1/sqrt(s/over + eps).

★ THE DIVIDE LIVES HERE, ONCE, ON PURPOSE. It used to be folded into the reduction’s scaler as 1/cols — but the reduce engine applies its scaler to EVERY TERM, so the chain computed Σ(xᵢ²·k) where the specification computes (Σxᵢ²)/cols. Equal in exact arithmetic, measurably different in floating point: each term picks up its own rounding. On the RDU’s bf16 datapath the legalized rmsnorm drifted a full ulp from the VM and spatial_front_end_lock caught it.

Widening the intermediates to fp32 changed the answer but did not fix it — which is the lesson. A decomposition’s numerics are not governed by intermediate PRECISION alone, but by which arithmetic is performed and where it narrows. Scale-once-at-the-end is part of the contract, so it is written into the op rather than left to a pass to remember.

Fields

eps_nano: u64

over: usize

Trait Implementations

impl Clone for RowXformKind

fn clone(&self) -> RowXformKind

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RowXformKind

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for RowXformKind

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Hash for RowXformKind

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for RowXformKind

fn eq(&self, other: &RowXformKind) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for RowXformKind

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for RowXformKind

impl Eq for RowXformKind

impl StructuralPartialEq for RowXformKind