Question 1

rpmalloc vs tcmalloc which is faster?

Accepted Answer

rpmalloc often outperforms tcmalloc in multithreaded scenarios due to its lock-free thread caching, as shown in benchmark charts in the README. However, performance varies based on allocation patterns, system cores, and configuration settings like cache sizes.

Question 2

How to override malloc with rpmalloc in Linux?

Accepted Answer

Compile rpmalloc with ENABLE_OVERRIDE defined to 1, then use LD_PRELOAD to inject the library into an existing binary. Alternatively, link it directly in your project and call rpmalloc_linker_reference to ensure override symbols are used for standard library functions.

Question 3

Is rpmalloc thread-safe for producer-consumer scenarios?

Accepted Answer

Yes, rpmalloc handles producer-consumer threads well with deferred frees to owning threads, reducing contention compared to some allocators. Freed blocks are reused quickly, but performance can degrade if thread cache thresholds are exceeded.

Question 4

Does rpmalloc support huge pages on macOS?

Accepted Answer

Yes, rpmalloc supports huge pages on Windows, Linux, and macOS. Enable it by passing a non-zero value in enable_huge_pages config during initialization with rpmalloc_initialize_config, and it automatically disables if unsupported.

Question 5

What are the memory overhead costs of rpmalloc?

Accepted Answer

rpmalloc aims to minimize overhead with efficient caching; benchmark data compares it to allocators like hoard and ptmalloc3. Overhead depends on thread cache settings and allocation patterns, but it's designed to be competitive without excessive waste.

Question 6

How to use first-class heaps in rpmalloc?

Accepted Answer

Define RPMALLOC_FIRST_CLASS_HEAPS to 1 during compilation, then use rpmalloc_heap_acquire and rpmalloc_heap_alloc APIs for scoped allocations. Note that this imposes a slight performance hit and the heap API is not thread-safe.

Question 7

Can rpmalloc be used in embedded systems with custom memory mapping?

Accepted Answer

Yes, rpmalloc allows custom memory mapping backends via rpmalloc_initialize_config, making it suitable for embedded systems. You must ensure alignment to the system page size, and it supports platforms with atomic operations.

rpmalloc

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