ec532e2c5c
The new feature, opt.percpu_arena, determines thread-arena association dynamically based CPU id. Three modes are supported: "percpu", "phycpu" and disabled. "percpu" uses the current core id (with help from sched_getcpu()) directly as the arena index, while "phycpu" will assign threads on the same physical CPU to the same arena. In other words, "percpu" means # of arenas == # of CPUs, while "phycpu" has # of arenas == 1/2 * (# of CPUs). Note that no runtime check on whether hyper threading is enabled is added yet. When enabled, threads will be migrated between arenas when a CPU change is detected. In the current design, to reduce overhead from reading CPU id, each arena tracks the thread accessed most recently. When a new thread comes in, we will read CPU id and update arena if necessary. |
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jemalloc | ||
msvc_compat |