From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Wagner <daniel.wagner@bmw-carit.de>
Subject: Re: [PATCH v3 2/4] KVM: use simple waitqueue for vcpu->wq
Date: Fri, 23 Oct 2015 13:51:05 +0200
Message-ID: <562A1F29.9000101@bmw-carit.de>
References: <1445326090-1698-1-git-send-email-daniel.wagner@bmw-carit.de>
 <1445326090-1698-3-git-send-email-daniel.wagner@bmw-carit.de>
 <20151020140031.GG17308@twins.programming.kicks-ass.net>
 <20151021092411.GD15591@fergus.ozlabs.ibm.com>
 <20151021111305.GL17308@twins.programming.kicks-ass.net>
Mime-Version: 1.0
Content-Type: text/plain; charset="windows-1252"
Content-Transfer-Encoding: 7bit
Cc: Peter Zijlstra <peterz@infradead.org>,
	<linux-kernel@vger.kernel.org>, <linux-rt-users@vger.kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Thomas Gleixner <tglx@linutronix.de>
To: Paul Mackerras <paulus@ozlabs.org>
Return-path: <linux-rt-users-owner@vger.kernel.org>
Received: from mail.bmw-carit.de ([62.245.222.98]:47665 "EHLO
	mail.bmw-carit.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751624AbbJWLvK (ORCPT
	<rfc822;linux-rt-users@vger.kernel.org>);
	Fri, 23 Oct 2015 07:51:10 -0400
In-Reply-To: <20151021111305.GL17308@twins.programming.kicks-ass.net>
Sender: linux-rt-users-owner@vger.kernel.org
List-ID: <linux-rt-users.vger.kernel.org>

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