DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=message-id:date:from:user-agent:mime-version:to:cc:subject
	:references:in-reply-to:content-type:content-transfer-encoding;
	b=kZM+D646uB+u7a3wjxm4u4Z+f78XbRCWdf078GafgO2SBfZUrXbJwaSILN61FujTNt
	dgwphk2rmsiXC7uBPAlk0BwDkpfn9zFloT9UU3KL4lX5w2Wmye0SBScEjytfo/soBeJs
	vxiH9DXL18NafO3uQVGqmG/hbiCmj6afSFQHw=
Message-ID: <4C7D5021.3090803@gmail.com>
Date: Tue, 31 Aug 2010 20:55:29 +0200
From: Yeb Havinga <yebhavinga@gmail.com>
User-Agent: Thunderbird 2.0.0.24 (Windows/20100228)
MIME-Version: 1.0
To: Scott Marlowe <scott.marlowe@gmail.com>
CC: Greg Smith <greg@2ndquadrant.com>,
	Jose Ildefonso Camargo Tolosa <ildefonso.camargo@gmail.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Performance on new 64bit server compared to my 32bit
 desktop
References: <4C6CE64D.6070104@edd.fr>	<4C6D76FE.9010407@2ndquadrant.com>
	<E613263E-09D5-4562-BBAF-C72B09883E26@richrelevance.com>
	<4C77F4F4.4020900@2ndquadrant.com>
	<AANLkTikd3BjGD+ti2RBrYu-2WJ7f-QM3dcJLMtYKOZUu@mail.gmail.com>
	<4C7B6498.5040800@gmail.com>	<4C7BCB2E.3090100@2ndquadrant.com>
	<4C7CF886.5040603@gmail.com>
	<AANLkTimvt54dduu8+MeHS6qcusO_AzCjkCzAQYMeSQmu@mail.gmail.com>
In-Reply-To: <AANLkTimvt54dduu8+MeHS6qcusO_AzCjkCzAQYMeSQmu@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

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