Revisiting the kernel's preemption models (part 1)
Revisiting the kernel's preemption models (part 1)
Posted Sep 21, 2023 21:26 UTC (Thu) by mtodorov (guest, #158788)In reply to: Revisiting the kernel's preemption models (part 1) by geofft
Parent article: Revisiting the kernel's preemption models (part 1)
I see your point. It could be reduced to checking a single variable telling which mode the system is currently in.
The locks which are currently held in a non-preemptible mode are obviously going to be held, but the idea behind locking is that it is short-held for performance reasons anyway.
I recall the kernel NMI timeouts on i.e. RCU locks being held for 20 seconds, but IMHO that is a sign of something deeply wrong in the kernel code ...
However, I have given up the idea that I will ever understand fully how +32M lines of code work and inter-operate.
Spinlocks are the idea of waiting from 6502 and Z80 and I think they're evil.