d419bb09ef
Simplify decay-based purging attempts to only be triggered when the epoch is advanced, rather than every time purgeable memory increases. In a correctly functioning system (not previously the case; see below), this only causes a behavior difference if during subsequent purge attempts the least recently used (LRU) purgeable memory extent is initially too large to be purged, but that memory is reused between attempts and one or more of the next LRU purgeable memory extents are small enough to be purged. In practice this is an arbitrary behavior change that is within the set of acceptable behaviors. As for the purging fix, assure that arena->decay.ndirty is recorded *after* the epoch advance and associated purging occurs. Prior to this fix, it was possible for purging during epoch advance to cause a substantially underrepresentative (arena->ndirty - arena->decay.ndirty), i.e. the number of dirty pages attributed to the current epoch was too low, and a series of unintended purges could result. This fix is also relevant in the context of the simplification described above, but the bug's impact would be limited to over-purging at epoch advances.
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, Valgrind integration, 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: http://www.canonware.com/jemalloc/