From mboxrd@z Thu Jan  1 00:00:00 1970
From: compudj@krystal.dyndns.org (Mathieu Desnoyers)
Date: Thu, 9 Jun 2011 10:43:29 -0400
Subject: [ltt-dev] [PATCH] call_rcu: keep BUSY flag set as long
	as	possible
In-Reply-To: <4DF0D6AD.7010500@redhat.com>
References: <1307523558-16960-1-git-send-email-pbonzini@redhat.com>
	<1307524638-17313-1-git-send-email-pbonzini@redhat.com>
	<BLU0-SMTP5719D5284785410F8A3E1396650@phx.gbl>
	<4DF0D6AD.7010500@redhat.com>
Message-ID: <BLU0-SMTP306E345FF419C077C3D88696650@phx.gbl>

* Paolo Bonzini (pbonzini at redhat.com) wrote:
> On 06/09/2011 04:09 PM, Mathieu Desnoyers wrote:
>> Would this be equivalent to not setting:
>>
>>    uatomic_set(&crdp->futex, 0);
>>
>> before breaking the loop, but then not decrementing
>>
>>    uatomic_dec(&crdp->futex);
>>
>> at the next loop iteration ?
>
> Something like that, yes.

Actually, my implementation had a problem with non-empty lists: it would
lead to decrementing the futex value below -1. commit
bc94ca9bada25f7403e3e859caa241146ae8e338 fixes this.

Thanks,

Mathieu

>
> Paolo
>

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com