RE: [BUG] Variable stopmachine_state should be volatile

From: Zhang, Yanmin <yanmin.zhang_at_intel.com>
Date: 2005-12-14 20:10:31
>>-----Original Message-----
>>From: linux-ia64-owner@vger.kernel.org
>>[mailto:linux-ia64-owner@vger.kernel.org] On Behalf Of Zhang, Yanmin
>>Sent: 2005年12月12日 15:07
>>To: Luck, Tony; Arjan van de Ven; Pavel Machek
>>Cc: linux-kernel@vger.kernel.org; Pallipadi, Venkatesh; Shah, Rajesh;
>>linux-ia64@vger.kernel.org
>>Subject: RE: [BUG] Variable stopmachine_state should be volatile
>>
>>>>-----Original Message-----
>>>>From: linux-ia64-owner@vger.kernel.org
>>>>[mailto:linux-ia64-owner@vger.kernel.org] On Behalf Of Luck, Tony
>>>>Sent: 2005年12月9日 2:53
>>>>To: Zhang, Yanmin; Arjan van de Ven; Pavel Machek
>>>>Cc: linux-kernel@vger.kernel.org; Pallipadi, Venkatesh; Shah, Rajesh;
>>>>linux-ia64@vger.kernel.org
>>>>Subject: RE: [BUG] Variable stopmachine_state should be volatile
>>>>
>>>>> The right approach is to define ia64_hint to ia64_barrier in file
>>>>> include/asm-ia64/intel_intrin.h. I tested the new approach and it
>>>>> does work.
>>>>
>>>>Does that get you a "hint@pause" instruction inside the loop?  If not, then
>>>>it isn't all the way to the "right" approach.
>>
>>Tony,
>>
>>The approach just fixes compiler scheduling barrier problem of cpu_relax, and
>>there is no hint@pause inside the loop.
>>
>>Today I tried the latest icc, 9.0.027. It provides __hint, a new intrinsic,
>>to support hint@pause. __hint also has the meaning of compiler scheduling
>>barrier. So the best solution is to use __hint(0). The disassembled result
>>showed the new intrinsic did work.
Tony,

Here is the patch against 2.6.15-rc5.

The latest intel compiler on ia64 also adds some other intrinsic, but I am not sure if they're useful in kernel except __hint, so I just enabled ia64_hint.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>


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Received on Wed Dec 14 20:11:10 2005

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