[LU-15718] lnet_selftest performance issues.

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.16.0
• Severity: 3
• Assignee: Alexey Lyashkov
• Reporter: Alexey Lyashkov

Description

High cpu usage seen while running a lnet_selftest with 3k-4k message size.
based on perf top it cause a spin lock contention in some area - 60%-70% cpu time spent for spin lock.
Looking a lnet selftest code founds an global spin lock protected whole work - new match bits allocation, stats, etc..
let's replace this lock is with atomic counters. this is reduce a lock contention by two.
second half separated by lnet resource and