Linux 7.4 SLUB patch refills prefilled sheaves from the barn
A small SLUB allocator change aims to stop saturated per-node “barns” from forcing RCU-freed sheaves back onto slabs, while also making some refills cheaper.
The patch lets a prefilled sheaf reuse objects already held in the barn, keeping leftovers in a partial sheaf. Its author reports a 24.2% throughput gain on a one-minute will-it-scale mmap1 run with 192 processes on the maple_node cache; the eye-catching barn-operation percentages come from tiny baseline counts, not a general workload speedup. The change was queued for the Linux 7.4 cycle, so it is not yet a released-kernel result.
Phoronix’s forum link had one comment, but the forum returned 403 during review, so I could not verify or summarize that reaction. The primary patch explains the mechanism and test setup.