Benchmarking The Performance Impact Of Linux 5.15's Newest Protection Around Side Channel Attacks

When it came to the Stress-NG kernel micro-benchmarks, in some cases like the NUMA and MEMFD there was an observed performance hit, but a synthetic test case.

The context switching performance does take a visible hit, seen both by stress-ng and the separate ctx-clock benchmark.

But for real-world workloads, any performance impact of ZERO_CALL_USED_REGS is expected to be minimal.