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From: Yeb Havinga <yebhavinga@gmail.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Greg Smith <greg@2ndquadrant.com>
Cc: Jose Ildefonso Camargo Tolosa <ildefonso.camargo@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Performance on new 64bit server compared to my 32bit desktop
Date: Tue, 31 Aug 2010 20:55:29 +0200
Message-ID: <4C7D5021.3090803@gmail.com> (raw)
In-Reply-To: <AANLkTimvt54dduu8+MeHS6qcusO_AzCjkCzAQYMeSQmu@mail.gmail.com>
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Scott Marlowe wrote:
> On Tue, Aug 31, 2010 at 6:41 AM, Yeb Havinga <yebhavinga@gmail.com> wrote:
>   
>>> export OMP_NUM_THREADS=4
>>>       
>> Then I get the following. The rather wierd dip at 5 threads is consistent
>> over multiple tries:
>>
>>     
>
> I get similar dips on my server.  Especially as you make the stream
> test write a large enough chunk of data to outrun its caches.
>
> See attached png.
>   
Interesting graph, especially since the overall feeling is a linear like 
increase in memory bandwidth when more cores are active.

Just curious, what is the 8-core cpu?

-- Yeb




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