From: | Pietro Pugni <pietro(dot)pugni(at)gmail(dot)com> |
---|---|
To: | Aidan Van Dyk <aidan(at)highrise(dot)ca> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL |
Date: | 2015-04-02 13:23:37 |
Message-ID: | 2EBBCD54-D3C8-436F-AF73-84EEF258AB70@gmail.com |
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Thread: | |
Lists: | pgsql-performance |
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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