Re: [PATCH] sched/core: Account PSI IRQ time to the execution context

[Hui Su]

> I did not construct a case where donor and curr differ.

I tested two proxy-execution processes in separate cgroup v2 cgroups.
The owner held a CPU0 mutex for 20s; a SCHED_FIFO donor blocked on it.
On x86_64 QEMU (4 vCPUs, 2 GiB), with PSI and IRQ time accounting enabled,
the irq.pressure total deltas (us) were:
  unpatched: owner 22,053, donor 401,127
  patched:   owner 552,740, donor 31,566
Both runs completed successfully, and attribution moved to execution context.
This exercises the donor != curr case missing from the original test.

Tested-by: Hui Su <sh_def@xxxxxxx>