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Message-ID: <4C4FE0CF.3070506@kernel.org>
Date: Wed, 28 Jul 2010 09:48:31 +0200
From: Tejun Heo <tj@...nel.org>
To: "Michael S. Tsirkin" <mst@...hat.com>
CC: Oleg Nesterov <oleg@...hat.com>,
Sridhar Samudrala <sri@...ibm.com>,
netdev <netdev@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Dmitri Vorobiev <dmitri.vorobiev@...ial.com>,
Jiri Kosina <jkosina@...e.cz>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...e.hu>, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH UPDATED 1/3] vhost: replace vhost_workqueue with per-vhost
kthread
On 07/27/2010 09:19 PM, Michael S. Tsirkin wrote:
>> Thinking a bit more about it, it kind of sucks that queueing to
>> another worker from worker->func() breaks flush. Maybe the right
>> thing to do there is using atomic_t for done_seq?
>
> I don't believe it will help: we might have:
>
> worker1 runs work
> work requeues itself queued index = 1
> worker1 reads queued index = 1
> worker2 runs work
> work requeues itself queued index = 2
> worker2 runs work
> worker2 reads queued index = 2
> worker2 writes done index = 2
> worker1 writes done index = 1
>
> As you see, done index got moved back.
Yeah, I think the flushing logic should be moved to the worker. Are
you interested in doing it w/ your change?
Thanks.
--
tejun
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