ULE scheduler: Interrupt thread natural binding to the core receiving the interrupt event is easily ignored

[jeff]

Summary

The ULE scheduler can break the natural affinity of the interrupt thread with the
core receiving the interruption event. If a core receives a hardware or software
interrupt, the common case outcome should be for the interrupt thread to be scheduled
immediately on the local core. With this particular issue in the ULE scheduler it
becomes likely that the local core will decide to schedule an interrupt thread on a
different core immediately.

Submitted by: Marc De La Gueronniere <[e-mail]>
MFC after: 1 week
Sponsored by: Verisign, Inc.

[jeff]

This looks correct to me. Do you have any information from testing? How was this found?

[jeff]

Taking this over to remind myself to commit it

[jhb]

The logic here changed quite a bit (possibly fixing this?) in c9205e35008e9275adb1803a10a7306c4f1c44a9.