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Message-ID: <530D5236.8090007@linux.vnet.ibm.com>
Date: Wed, 26 Feb 2014 10:32:22 +0800
From: Michael wang <wangyun@...ux.vnet.ibm.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: Sasha Levin <sasha.levin@...cle.com>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: sched: hang in migrate_swap
On 02/25/2014 06:49 PM, Peter Zijlstra wrote:
> On Tue, Feb 25, 2014 at 12:47:01PM +0800, Michael wang wrote:
>> On 02/24/2014 09:10 PM, Peter Zijlstra wrote:
>>> On Mon, Feb 24, 2014 at 01:12:18PM +0100, Peter Zijlstra wrote:
>>>> + if (p) {
>>>> + if (unlikely(p == RETRY_TASK))
>>>> + goto again;
>>>
>>> We could even make that: unlikely(p & 1), I think most CPUs can encode
>>> that far better than the full pointer immediate.
>>
>> Agree, unless odd-align stuff appeared...
>
> That shouldn't happen; we rely on u32 alignment all over the place. So
> for general objects we should have at least the lower two bits free to
> play with.
Make sense :)
Regards,
Michael Wang
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