[Lustre-discuss] 1.6.4.3 changes CPU mapping in RHEL., and 10x performance loss in one application

[Aaron Knister]

Did you ever find a resolution? And out of curiosity, how did you  
determine that the core to logical processor allocation had changed?  
I'm trying to figure it out in my own set up.

-Aaron

On Apr 10, 2008, at 2:13 PM, Chris Worley wrote:

> On Thu, Apr 10, 2008 at 12:05 PM, Johann Lombardi <johann at sun.com>  
> wrote:
>> Chris,
>>
>>
>> On Sat, Apr 05, 2008 at 06:11:32PM -0600, Chris Worley wrote:
>>> I was running RHEL's 2.6.9-67.0.4 kernel w/o Lustre patches, and the
>>
>> What is the CPU architecture? x86_64 or IA64?
>
> x86_64.
>
>>
>>
>>> core to logical processor allocation was (as shown by /proc/ 
>>> cpuinfo):
>>>
>>>
>>>       =============      =============    Socket
>>>
>>>       ====== ======       ======  ======    L2 cache domain
>>>
>>>        0    4      1     5          2      6     3     7      
>>> logical processor
>>>
>>>
>>> After installing the Lustre version of the kernel, the allocation  
>>> is:
>>>
>>>       =============      =============    Socket
>>>
>>>       ======  ======      ======  ======    L2 cache domain
>>>
>>>        0     1      2      3        4      5      6    7      
>>> logical processor
>>
>> Hard to believe that one of our patches could cause this.
>> Have you compared the kernel config files?
>
> This is the default from RedHat vs. the default from
> downloads.lustre.org.  We didn't rebuild either from scratch.
>
> Chris
>>
>> Cheers,
>> Johann
>>
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Aaron Knister
Associate Systems Analyst
Center for Ocean-Land-Atmosphere Studies

(301) 595-7000
aaron at iges.org