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A comment on Jemalloc 5.4.0. Parent comment

Re:Jemalloc 5.4.0 by jeffbee on Friday September 18, 2026 @11:41AM (#49756027)
Exactly. You want memory arenas that are hot in this CPU's caches. If your thread moves, its per-thread caches are now elsewhere. Original TCMalloc was developed in the days of 2-4 core servers. Current TCMalloc was an evolution in the context of 32+ core servers.
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Re:Jemalloc 5.4.0 by skavi on Friday September 18, 2026 @01:28PM (#49757529)
my feeling is that the space efficiency gains are probably more significant than the reduction in core migration costs. many applications have far more threads than the system has cores.
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Re:Jemalloc 5.4.0 by jeffbee on Friday September 18, 2026 @01:30PM (#49757561)
Sure, also true that the per-CPU scheme co-evolved with the proliferation of services with thread-per-request architectures having way more TIDs than cores.
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