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db15a39d75
9c1a484e embedded sec_t in pac_t (+~48B). Since pac sits before the hot
hpa/edata_cache fields in pa_shard_s, the larger pac_t shifts them and
regresses the free/extent paths ~2% on the fill-flush microbenchmark --
even though SEC is disabled by default and no SEC code runs; it is purely
a struct-layout effect.
Move pac to the last field so its growth shifts only the trailing
all_bins[] flex array. Pure reorder, no functional change.
Validated with the fill-flush microbenchmark (500 threads, 256 B,
MALLOC_CONF=tcache:true,prof:true), turbo pinned, interleaved medians:
on AMD EPYC 9D64 (x86-64) bad regresses ~2% and the reorder restores the
baseline; on ARM Neoverse-V2 (aarch64) there is no measurable regression
and the reorder is neutral.jemalloc is a general purpose malloc(3) implementation that emphasizes fragmentation avoidance and scalable concurrency support. jemalloc first came into use as the FreeBSD libc allocator in 2005, and since then it has found its way into numerous applications that rely on its predictable behavior. In 2010 jemalloc development efforts broadened to include developer support features such as heap profiling and extensive monitoring/tuning hooks. Modern jemalloc releases continue to be integrated back into FreeBSD, and therefore versatility remains critical. Ongoing development efforts trend toward making jemalloc among the best allocators for a broad range of demanding applications, and eliminating/mitigating weaknesses that have practical repercussions for real world applications. The COPYING file contains copyright and licensing information. The INSTALL file contains information on how to configure, build, and install jemalloc. The ChangeLog file contains a brief summary of changes for each release. URL: https://jemalloc.net/