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Signed-off-by: Joe Isaacs <joe.isaacs@live.co.uk>

Author: joseph-isaacs

vortex-compute/src/lane_kernels/map_in_place.rs

@@ -8,6 +8,7 @@
 
 use vortex_buffer::BitBuffer;
 
+use crate::lane_kernels::CHUNK_LEN;
 use crate::lane_kernels::sink::IndexedSink;
 
 /// Extension trait providing in-place lane-kernel methods on any [`IndexedSink`].
@@ -54,14 +55,14 @@ pub trait IndexedSinkExt: IndexedSink + Sized {
 
         let mut values = self;
         let len = values.len();
-        let chunks_count = len / 64;
-        let remainder = len % 64;
+        let chunks_count = len / CHUNK_LEN;
+        let remainder = len % CHUNK_LEN;
 
         for chunk_idx in 0..chunks_count {
-            chunk(&mut values, &mut f, chunk_idx * 64, 64);
+            chunk(&mut values, &mut f, chunk_idx * CHUNK_LEN, CHUNK_LEN);
         }
         if remainder != 0 {
-            chunk(&mut values, &mut f, chunks_count * 64, remainder);
+            chunk(&mut values, &mut f, chunks_count * CHUNK_LEN, remainder);
         }
     }
 

vortex-compute/src/lane_kernels/map_into.rs

@@ -8,6 +8,7 @@ use std::mem::MaybeUninit;
 
 use vortex_buffer::BitBuffer;
 
+use crate::lane_kernels::CHUNK_LEN;
 use crate::lane_kernels::source::IndexedSource;
 
 /// Extension trait providing out-of-place lane-kernel methods on any [`IndexedSource`].
@@ -144,14 +145,14 @@ pub trait IndexedSourceExt: IndexedSource + Sized {
         let len = values.len();
         assert_eq!(out.len(), len, "out must have the same length as values");
 
-        let chunks_count = len / 64;
-        let remainder = len % 64;
+        let chunks_count = len / CHUNK_LEN;
+        let remainder = len % CHUNK_LEN;
 
         for chunk_idx in 0..chunks_count {
-            chunk(&values, out, &mut f, chunk_idx * 64, 64);
+            chunk(&values, out, &mut f, chunk_idx * CHUNK_LEN, CHUNK_LEN);
         }
         if remainder != 0 {
-            chunk(&values, out, &mut f, chunks_count * 64, remainder);
+            chunk(&values, out, &mut f, chunks_count * CHUNK_LEN, remainder);
         }
     }
 
@@ -216,17 +217,17 @@ pub trait IndexedSourceExt: IndexedSource + Sized {
         let len = values.len();
         assert_eq!(out.len(), len, "out must have the same length as values");
 
-        let chunks_count = len / 64;
-        let remainder = len % 64;
+        let chunks_count = len / CHUNK_LEN;
+        let remainder = len % CHUNK_LEN;
 
         for chunk_idx in 0..chunks_count {
-            let base = chunk_idx * 64;
-            if chunk(&values, out, &mut f, base, 64) {
-                return Err(attribute_failure_no_mask(&values, base, 64, &mut f));
+            let base = chunk_idx * CHUNK_LEN;
+            if chunk(&values, out, &mut f, base, CHUNK_LEN) {
+                return Err(attribute_failure_no_mask(&values, base, CHUNK_LEN, &mut f));
             }
         }
         if remainder != 0 {
-            let base = chunks_count * 64;
+            let base = chunks_count * CHUNK_LEN;
             if chunk(&values, out, &mut f, base, remainder) {
                 return Err(attribute_failure_no_mask(&values, base, remainder, &mut f));
             }

vortex-compute/src/lane_kernels/mod.rs

@@ -33,3 +33,17 @@ pub use sink::IndexedSink;
 pub use sink::ReinterpretSink;
 pub use source::IndexedSource;
 pub use source::LaneZip;
+
+/// Loop-tiling chunk length for the **no-mask** kernels ([`IndexedSourceExt::map_into`],
+/// [`IndexedSourceExt::try_map_into`], [`IndexedSinkExt::map_into_in_place`]).
+///
+/// This is a pure tuning knob: those kernels split the lane range into
+/// `len / CHUNK_LEN` full chunks plus a remainder, so any value yields correct
+/// results and only the codegen/tiling changes. Vary it to tune performance.
+///
+/// It does **not** apply to the masked or bit-packed kernels: those consume one
+/// [`BitBuffer::chunks`] u64 validity word per chunk and pack per-lane fail bits
+/// with `<< bit_idx` into a `u64`, so their chunk length is locked to 64.
+///
+/// [`BitBuffer::chunks`]: vortex_buffer::BitBuffer::chunks
+pub(crate) const CHUNK_LEN: usize = 64;