Messages in this thread | | | Date | Tue, 20 Jul 2004 21:25:57 -0400 | From | Timothy Miller <> | Subject | Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel Preemption Patch |
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Lee Revell wrote:
> There are still a few areas that need work, ioctl gives me problems, but > the latest 2.6 kernels are quite good. If you look at the 'clean' > version of the voluntary kernel preemption patch it is pretty small. My > understanding is that the kernel is already preemptible anytime that a > spin lock (including the BKL) is not held, and that the voluntary kernel > preemption patch adds some scheduling points in places where it is safe > to sleep, but preemption is disabled because we are holding the BKL, and > that the number of these should approach zero as the kernel is improved > anyway.
That's confusing to me. It was my understanding that the BKL is used to completely lock down the kernel so that no other CPU can have a process get into the kernel... something like how SMP was done under 2.0.
So, if you sleep during a BKL, wouldn't that imply that nothing else would be allowed to enter the kernel until after the kernel thread that took the lock wakes up and releases the lock?
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