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Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL - Mailing list pgsql-performance

From Pietro Pugni
Subject Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL
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Msg-id 2EBBCD54-D3C8-436F-AF73-84EEF258AB70@gmail.com
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In response to Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL  (Aidan Van Dyk <aidan@highrise.ca>)
Responses Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL
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Hi Aidan,

 
T420
work_mem = 512MB
 
MacMini
work_mem = 32MB

So that is why the T420 does memory sorts and the mini does disk sorts.

I'd start looking at why memory sorts on the T420 is so slow.   Check your numa settings, etc (as already mentioned).

For a drastic test, disable the 2nd socket on the dell, and just use one (eliminate any numa/QPI costs) and see how it compares to the no-numa MacMini.


the command 
dmesg | grep -i numa
doesn’t display me anything. I think T420 hasn’t NUMA on it. Is there a way to enable it from Ubuntu? I don’t have immediate access to BIOS (server is in another location).
For QPI I don’t know what to do. Please, can you give me more details?

If you want to see how bad the NUMA/QPI is, play with stream to benchmark memory performance.

With stream you refer to this: https://sites.utexas.edu/jdm4372/tag/stream-benchmark/ ? Do you suggest me some way to do this kind of tests?

Thank you very much 
 Pietro

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