Messages in this thread | | | Date | Fri, 10 Oct 2003 11:29:09 -0700 | From | William Lee Irwin III <> | Subject | Re: 2.7 thoughts |
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On Fri, Oct 10, 2003 at 07:47:23AM -0700, William Lee Irwin III wrote: >> You need at least enough warning to get out of critical sections (e.g. >> holding a spinlock) and dump registers out to memory. i.e. as long as it >> takes to schedule out whatever's currently running on the thing.
On Fri, Oct 10, 2003 at 11:03:20AM -0700, Tim Hockin wrote: > I've got a patch against RedHat's 2.4.x kernel with some version of O(1) > scheduler that migrates all processes off a CPU and makes it ineleigible to > run new tasks. When the syscall returns, it is safe to remove the CPU. > Processes that are running or sleeping and can be migrated elsewhere are > migrated. Running processes that have set_cpus_allowed to ONLY the > processor in question are marked TASK_UNRUNNABLE and moved off the runqueue. > Sleeping processes that have set_cpus_allowed to ONLY the processor in > question are left unmolested until they wake up, at which point they will be > marked UNRUNNABLE. > It was done to allow software to bring CPUs on/offline, but it should work > for this. IRQs not done yet, either.
I think there is some generalized cpu hotplug stuff that's gone in that direction already, though I don't know any details. The bits about non- cooperative offlining were very interesting to hear, though.
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