svn commit: r211176 - in head/sys: amd64/amd64 i386/i386

Attilio Rao attilio at
Wed Aug 11 11:21:48 UTC 2010

2010/8/11 Kostik Belousov <kostikbel at>:
> On Wed, Aug 11, 2010 at 10:51:27AM +0000, Attilio Rao wrote:
>> Author: attilio
>> Date: Wed Aug 11 10:51:27 2010
>> New Revision: 211176
>> URL:
>> Log:
>>   IPI handlers may run generally with interrupts disabled because they
>>   are served via an interrupt gate.
>>   However, that doesn't explicitly prevent preemption and thread
>>   migration thus scheduler pinning may be necessary in some handlers.
>>   Fix that.
> How the preemption is supposed to happen ? Aside from the explicit
> calls to mi_switch() from e.g. critical_exit().

IIRC it should be hardclock() willing to schedule the softclock(). It
is the critical_exit() in the thread_unlock() that may trigger it
(sorry for not digging more, it was a while back that I hacked this
part, but I guess you can verify on your own).
We already have other points within the kernel that take care of
dealing with preemption/migration like lapic_handle_timer(), for


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