Hello, LSF. Title: Introduce a per-cpu-vmap-cache to eliminate a vmap lock contention Description: Currently the vmap code is not scaled to number of CPU cores in a system because a global vmap space is protected by a single spinlock. Such approach has a clear bottleneck if many CPUs simultaneously access to one resource. In this talk i would like to describe a drawback, show some data related to contentions and places where those occur in a code. Apart of that i would like to share ideas how to eliminate it providing a few approaches and compare them. Requirements: * It should be a per-cpu approach; * Search of freed ptrs should not interfere with other freeing(as much as we can); * - offload allocated areas(buzy ones) per-cpu; * Cache ready sized objects or merge them into one big per-cpu-space(split on demand); * Lazily-freed areas either drained per-cpu individually or by one CPU for all; * Prefetch a fixed size in front and allocate per-cpu Goals: * Implement a per-cpu way of allocation to eliminate a contention. Thanks! -- Uladzislau Rezki
