Re: [RFC PATCH 0/3] Fix SLQB on memoryless configurations V2

Sachin Sant
2009-09-22T13:05:11Z

Mel Gorman wrote:
> On Tue, Sep 22, 2009 at 10:33:11AM +0530, Sachin Sant wrote:
>
>> Mel Gorman wrote:
>>
>>> On Mon, Sep 21, 2009 at 01:54:12PM -0400, Christoph Lameter wrote:
>>>
>>>
>>>> Lets just keep SLQB back until the basic issues with memoryless nodes are
>>>> resolved.
>>>>
>>>>
>>> It's not even super-clear that the memoryless nodes issues are entirely
>>> related to SLQB. Sachin for example says that there was a stall issue
>>> with memoryless nodes that could be triggered without SLQB. Sachin, is
>>> that still accurate?
>>>
>>>
>> I think there are two different problems that we are dealing with.
>>
>> First one is the SLQB not working on a ppc64 box which seems to be specific
>> to only one machine and i haven't seen that on other power boxes.The patches
>> that you have posted seems to allow the box to boot, but eventually it hits
>> the stall issue(related to percpu dynamic allocator not working on ppc64),
>> which is the second problem we are dealing with.
>>
>>
>
> Ok, I've sent out V3 of this. It's only a partial fix but it's about as
> far as it can be brought until the other difficulties are resolved.
>
Thanks Mel.

>
>> The stall issue seems to be much more critical as it is affecting almost
>> all of the power boxes that i have tested with (4 in all).
>> This issue is seen with Linus tree as well and was first seen with
>> 2.6.31-git5 (0cb583fd..)
>>
>> The stall issue was reported here:
>> http://lists.ozlabs.org/pipermail/linuxppc-dev/2009-September/075791.html
>>
>>
>
> Can you bisect this please?
>
The problem seems to have been introduced with
commit ada3fa15057205b7d3f727bba5cd26b5912e350f.

Specifically this patch :
powerpc64: convert to dynamic percpu allocator

If i revert this patch i am able to boot latest git
on a powerpc box.

Thanks
-Sachin

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Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
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