This crate provides proc macro attributes to improve in memory data access times.

Cuneiform's main macro can take various arguments at attribute position:

• hermetic = true|false (default is true when #[cuneiform])
  • Hermetic enables cuneiform to detect cache sizes from OSes which have API to fetch.
  • Currently, hermetic argument works only Linux kernel 2.6.32 and above.
  • If system is different than supported systems it falls back to slabs.
• slab = "board_or_architecture_name (e.g. #[cuneiform(slab = "powerpc_mpc8xx")])
  • Slabs are either embedded system boards or other specific architecture.
  • Slab checking have two stages:
    • First, it checks the given board/architecture if exist.
    • If not slabs fall back to Rust supported architectures.
    • Still architecture is not detected, it will fall back to default values.
• force = u8 (e.g. #[cuneiform(force = 16)])
  • Forces a given cache alignment. Overrides all other systems mentioned above.

[dependencies]
cuneiform = "0.1"

Examples

Basic usage can be:

// Defaults to `hermetic = true`
#[cuneiform]
pub struct Varying {
    data: u8,
    data_2: u16,
}

Targeting specific architecture:

#[cuneiform(slab = "powerpc_mpc8xx")]
pub struct SlabBased {
    data: u8,
    data_2: u16,
}

Overriding the default cache alignment:

#[cuneiform(force = 16)]
pub struct Forced {
    data: u8,
    data_2: u16,
}

Field level cache optimizations

Check out cuneiform-fields for field level optimizations.

Design choices

• Cuneiform doesn't have specific instruction or architecture specific code.
• Works with crates like #![no_std]. Ease your pain for cache optimizations. With allocator you can compile on the board too.
• Not based on assumptions. Based on Linux tree, OS checks, provider manuals and related documentation.

Before opening a PR

• If it is big.LITTLE architecture, separate both parts in slabs. Apply the naming conventions.
• Check existing slabs before opening a PR. Please update it when you add one.
• If you come up with instructionless detection for hermetic alignment. Be sure that tests are included and not breaking existing platforms.

Existing Slabs

• powerpc_mpc8xx
• powerpc64bridge
• powerpc_e500mc
• power_7
• power_8
• power_9
• exynos_big
• exynos_LITTLE
• krait
• neoverse_n1