Messages in this thread | | | Subject | Re: [PATCH] Allow preemption during lazy mmu updates | From | Peter Zijlstra <> | Date | Sun, 19 Apr 2009 12:47:25 +0200 |
| |
On Sun, 2009-04-19 at 13:15 +0300, Avi Kivity wrote: > Peter Zijlstra wrote: > > On Wed, 2009-04-08 at 16:54 +0200, Ingo Molnar wrote: > > > >>> kernel/sched.c | 2 - > >>> > >> Needs the ack of ... oh, never mind - this one is fine i guess ;-) > >> > > > > Ah, about that. This new preemption hook has slightly different > > requirements than the current preempt-notifiers have (hence the new > > hook), I was wondering if KVM (afaik currently the only preempt-notifier > > consumer) could live with these requirements. > > > > That is, could these be merged? > > > > What are the slight differences in requirements? > > KVM wants to run in non-preemptible, interrupts-enabled context.
The fire_sched_out bit is a little earlier, but I don't think that is a particularly worrysome, but the most important difference was that fire_sched_in in far too late. arch_end_context_switch() is done right in the middle of switch_to() because it needs the TS bit or somesuch.
I'll let Jeremy explain details, as I've long since forgotten them :-)
| |