Re: [PATCH] kvm: add halt_poll_ns module parameter
From: Radim KrÄmÃÅ
Date: Mon Feb 09 2015 - 12:28:33 EST
2015-02-09 17:10+0100, Paolo Bonzini:
> On 09/02/2015 16:21, Radim KrÄmÃÅ wrote:
> > 2015-02-06 13:48+0100, Paolo Bonzini:
> >> +TRACE_EVENT(kvm_vcpu_wakeup,
> >> + TP_PROTO(__u64 ns, bool waited),
> > (__u64 is preferred here?)
> Preferred to what?
To 'u64'. (The header file shouldn't be reachable from user-space.)
> >> + } while (single_task_running() && ktime_before(cur, stop));
> > After reading a bunch of code, I'm still not sure ...
> > - need_resched() can't be true when single_task_running()?
> > (I think it could happen -- balancing comes into mind.)
> Single_task_running is per-CPU; for a task to relinquish control to
> another task, you first need to have multiple tasks running. In other
> words, I think it cannot.
Ok, thanks. (I thought that need_resched has more general meaning and
couldn't confirm that balancing/CPU-offlining/... just evicts the task
without waiting for its schedule().)
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