Mr. Morton speaks

If you’re a geek who loves geek-speak, I’ve got just the thing for you. On the other hand, if you’re simply curious about Andrew Morton and wonder what the man who maintains the Linux kernel is thinking…well, I’ve got something for you, too.

KernelTrap has posted an interview with Andrew conducted in February of 2002. In it he gives us insights into what a Linux maintainer does, as well as how patches are added to the kernel and the process involved in releasing a new kernel version to the Linux community. “The approach taken by these patches is basically cooperative multitasking. The developer identifies sections of long-running kernel code and changes them so that they will yield the CPU to another task if the scheduler says that it’s time to do that.

Most of the complexity here is in being able to back out of any locking before yielding, and in cleanly reacquiring locking state when the interrupted task resumes. With an internally preemptible kernel the explicit task yielding is not necessary, because the context switch is performed in the interrupt return path and via open-coded yields which are hidden in the unlock code. But you cannot preempt an in-kernel process while it holds locks, so all the unlock, relock and fixup code is needed in either approach.

The filesystem is absolutely paranoid about looking after your data - it has 150 internal consistency checks, any one of which will deliberately crash your machine if it is violated. This protects your data from both software and hardware bugs, and ensures that the developers get to hear about any problems. That is just good, hard-nosed engineering practice.”

If this kind of talk gets your mental gears spinnig, head on over to KernalTrap for the full interview. Then you can write to me and tell me what he’s talking about. OK?