879e76a9e5
This provides in-place expansion of huge allocations when the end of the allocation is at the end of the sbrk heap. There's already the ability to extend in-place via recycled chunks but this handles the initial growth of the heap via repeated vector / string reallocations. A possible future extension could allow realloc to go from the following: | huge allocation | recycled chunks | ^ dss_end To a larger allocation built from recycled *and* new chunks: | huge allocation | ^ dss_end Doing that would involve teaching the chunk recycling code to request new chunks to satisfy the request. The chunk_dss code wouldn't require any further changes. #include <stdlib.h> int main(void) { size_t chunk = 4 * 1024 * 1024; void *ptr = NULL; for (size_t size = chunk; size < chunk * 128; size *= 2) { ptr = realloc(ptr, size); if (!ptr) return 1; } } dss:secondary: 0.083s dss:primary: 0.083s After: dss:secondary: 0.083s dss:primary: 0.003s The dss heap grows in the upwards direction, so the oldest chunks are at the low addresses and they are used first. Linux prefers to grow the mmap heap downwards, so the trick will not work in the *current* mmap chunk allocator as a huge allocation will only be at the top of the heap in a contrived case. |
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internal | ||
jemalloc_defs.h.in | ||
jemalloc_macros.h.in | ||
jemalloc_mangle.sh | ||
jemalloc_protos.h.in | ||
jemalloc_rename.sh | ||
jemalloc_typedefs.h.in | ||
jemalloc.sh |