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Implementation inspired by idea described in "Beyond malloc efficiency to fleet efficiency: a hugepage-aware memory allocator" paper [1]. Primary idea is to track maximum number (peak) of active pages in use with sliding window and then use this number to decide how many dirty pages we would like to keep. We are trying to estimate maximum amount of active memory we'll need in the near future. We do so by projecting future active memory demand (based on peak active memory usage we observed in the past within sliding window) and adding slack on top of it (an overhead is reasonable to have in exchange of higher hugepages coverage). When peak demand tracking is off, projection of future active memory is active memory we are having right now. Estimation is essentially the same as `nactive_max * (1 + dirty_mult)`. Peak demand purging algorithm controlled by two config options. Option `hpa_peak_demand_window_ms` controls duration of sliding window we track maximum active memory usage in and option `hpa_dirty_mult` controls amount of slack we are allowed to have as a percent from maximum active memory usage. By default `hpa_peak_demand_window_ms == 0` now and we have same behaviour (ratio based purging) that we had before this commit. [1]: https://storage.googleapis.com/gweb-research2023-media/pubtools/6170.pdf
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/