The kernel address space isolation makes syscalls much more expensive than they were. A toy program that just repeatedly calls the cheapest syscall in the kerne

The kernel address space isolation makes syscalls much more expensive than they were. A toy program that just repeatedly calls the cheapest syscall in the kernel would lose much more than half it's speed, but that's not what's reported because no-one actually needs to run that workload. Epic seems to have been particularly unlucky in how KPTI impacts them.