expire running dead slow

anne anne at unidata.ucar.edu
Tue Aug 24 17:25:44 UTC 2004


The HT thought made me recall something:

Are your running a RAID?  We have seen 2 cases where Linux performed 
signficantly better with software RAID control after disabling the 
hardware RAID controller.  Unexpected, but true.  One these machines 
was, like yours, a dual HT Xeon.  FWIW.

Anne


Mark Hittinger wrote:
>>>>I have a machine, 1 of 6, running INN 2.4.1 on an Intel platform. CNFS
>>>>storage, about 8TB, dual 2.8GHz HT Xeons, 2.5GB memory. Redhat
>>>>Enterprise AS3.0.
>>>>This is one of our small regional servers. For some reason, expire on
>>>>this machine takes forever to do expire every few days, anywhere from
>>>>35-50 hours. At other times it runs only 1-2 hours. We have about 22M
>>>>articles in history, INN is built largefile enabled, obviously.
>>
>>...
> 
> 
>>Other ideas desperately embraced.
> 
> 
> Try disabling HT.  I have some applications that will get queued to run
> on the "logical" cpu on systems with HT enabled and they will slow way down.
> 
> This might explain the 2 hours vs. 35 hours.
> 
> Disabling HT will force the expire to run on one of the "real" cpu's.
> 
> It is particularly bad if the applications that get queued to the "logical"
> cpu own locks.
> 
> Since you have dual Xeon's you have to run the smp kernel but I think you
> should be able to disable HT in the bios.
> 
> BTW have you compiled inn with gcc 3.4.0 -O3?  On number crunching stuff
> (particularly floating point) the newer gcc is able to do some better Intel
> optimization - but that might be more noticeable on the northwood/prescott
> cpu rather than the xeon.  On I/O bound inn who knows? :-)
> 
> Later
> 
> Mark Hittinger
> bugs at pu.net

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Anne Wilson                     UCAR Unidata Program
anne at unidata.ucar.edu                  P.O. Box 3000
                                   Boulder, CO  80307
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