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Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq

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Hi Paul,

On 10/21/2015 01:13 PM, Peter Zijlstra wrote:
> On Wed, Oct 21, 2015 at 08:24:11PM +1100, Paul Mackerras wrote:
>> On Tue, Oct 20, 2015 at 04:00:31PM +0200, Peter Zijlstra wrote:
>>>
>>> Should we not take this opportunity to get rid of these open-coded wait
>>> loops?
>>>
>>>
>>> Does this work?
>>
>> No, on Book3S HV (POWER8) the VM hangs immediately after the kernel
>> brings up all the secondary vCPUs, and is then unkillable.  I'm not
>> sure what's wrong, although I wonder why you have TASK_IDLE rather
>> than TASK_INTERRUPTIBLE in the ___wait_event call.
> 
> This was under the assumption that INTERRUPTIBLE was because you wanted
> to avoid increasing load. Which was based on the lack of
> signal_pending() tests near there (although there might have been in the
> outermost loop which I overlooked).
> 
> If it does rely on signals, then this was obviously false and TASK_IDLE
> is indeed wrong.

If I get this right, the current patch is okay but you are going to
redactor the code? Maybe I can cherry pick your patch then and update
this patch accordingly.

cheers,
daniel
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[PATCH v3 0/4] Simple wait queue support Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-10-20 09:30 +0200
  [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-10-20 09:30 +0200
    Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Paolo Bonzini <pbonzini@redhat.com> - 2015-10-20 15:20 +0200
    Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Peter Zijlstra <peterz@infradead.org> - 2015-10-20 16:10 +0200
      Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Paolo Bonzini <pbonzini@redhat.com> - 2015-10-20 17:50 +0200
        Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Peter Zijlstra <peterz@infradead.org> - 2015-10-20 18:10 +0200
      Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Paul Mackerras <paulus@ozlabs.org> - 2015-10-21 11:00 +0200
        Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Peter Zijlstra <peterz@infradead.org> - 2015-10-21 11:10 +0200
      Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Paul Mackerras <paulus@ozlabs.org> - 2015-10-21 11:20 +0200
      Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Paul Mackerras <paulus@ozlabs.org> - 2015-10-21 11:30 +0200
        Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Peter Zijlstra <peterz@infradead.org> - 2015-10-21 13:20 +0200
          Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-10-23 14:00 +0200
  [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait) implementation Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-10-20 09:30 +0200
    Re: [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait)  implementation Boqun Feng <boqun.feng@gmail.com> - 2015-10-26 13:10 +0100
      Re: [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait)  implementation Peter Zijlstra <peterz@infradead.org> - 2015-10-26 13:30 +0100
      Re: [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait)  implementation Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-10-26 14:00 +0100
        Re: [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait)  implementation Peter Zijlstra <peterz@infradead.org> - 2015-10-26 15:00 +0100
          Re: [PATCH v3 1/4] wait.[ch]: Introduce the simple waitqueue (swait)  implementation Boqun Feng <boqun.feng@gmail.com> - 2015-10-26 15:30 +0100
  Re: [PATCH v3 0/4] Simple wait queue support "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-25 21:20 +0100
    Re: [PATCH v3 0/4] Simple wait queue support Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-10-26 07:40 +0100

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