Crate tcmalloc_better

A drop-in global allocator wrapper around the TCMalloc allocator. TCMalloc is a general-purpose, performance-oriented allocator built by Google.

Usage

use tcmalloc_better::TCMalloc;

#[global_allocator]
static GLOBAL: TCMalloc = TCMalloc;

fn main() {
    TCMalloc::process_background_actions_thread();

    // Rest of main
}

Caveats

This library is intended for use on Linux (x86_64, aarch64). For applications requiring support on a broader range of platforms, consider using malloc-best-effort, which automatically selects the best allocator based on the target platform.

Feature flags

• std (enabled by default) — enable std
• extension (enabled by default) — TCMalloc extension API
• numa_aware — Enable NUMA-aware allocation. Need to use TCMALLOC_NUMA_AWARE environment variable at runtime. See TCMalloc comments
• deprecated_perthread — Use deprecated per-thread caching. Newer systems with Linux kernel version >= 4.18 should not use this.
• legacy_locking — Use legacy locking backend (which is not TLB-aware) See TCMalloc docs
• realloc — Use TCMalloc’s realloc instead of default GlobalAlloc::realloc. Caveats: All memory deallocations will use the slower unsized TCMallocInternalDeleteAligned (which accesses slow page map). Enable this feature only if you frequently use realloc operations which resides in same size class or same kPageSize-sized blocks, and only after performance measurements or benchmarking. Rust standard library uses realloc of such conditions mainly for manually shrinking operations. Reallocation for growing operation increments size twice, so it will not be the same size class anyway in such case.

Logical Page Sizes (These features are mutually exclusive).

Larger page size leads to greater performance in expense to increased fragmentation. See TCMalloc tuning guide:

• 8k_pages (enabled by default) — 8k pages
• 32k_pages — Large pages
• 256k_pages — 256k pages
• small_but_slow — 4k pages, option for memory constrained systems

Madvise Transparent Hugepages control (Use no more than one value)

By default, if none of these features are enabled, madvise hugepages will be enabled:

• disable_madv_hugepage_always — Disable madvise hugepages
• disable_madv_hugepage_by_var — Disable madvise hugepages via environment variable TCMALLOC_DISABLE_MADV_HUGEPAGE at runtime. This variable can be set to 0 or 1 to enable or disable madvise hugepages respectively.

Structs

TCMalloc

A memory allocator that can be registered as the standard library’s default through the #[global_allocator] attribute.