Re: Adding more memory = hugh cpu load [solved] - Mailing list pgsql-performance

From Arjen van der Meijden
Subject Re: Adding more memory = hugh cpu load [solved]
Date
Msg-id 4E94A828.1040201@tweakers.net
Whole thread Raw
In response to Re: Adding more memory = hugh cpu load [solved]  (Claudio Freire <klaussfreire@gmail.com>)
Responses Re: Adding more memory = hugh cpu load [solved]  (Claudio Freire <klaussfreire@gmail.com>)
List pgsql-performance
On 11-10-2011 20:05 Claudio Freire wrote:
> On Tue, Oct 11, 2011 at 3:02 PM, alexandre - aldeia digital
> <adaldeia@gmail.com>  wrote:
>> 2) Change all memory chips to new others, instead of maintain the old (16
>> GB) + new (32 GB).
>
> Of course, mixing disables double/triple/whatuple channel, and makes
> your memory subsystem correspondingly slower.
> By a lot.
>

That really depends on the chipset/server. The current intel E56xx-chips
(and previous E55xx) basically just expect groups of 3 modules per
processor, but it doesn't really matter whether that's 3x2+3x4 or 6x4 in
terms of performance (unless the linuxkernel does some weirdness of
course). It at least won't disable triple-channel, just because you
added different size modules. Only when you get to too many 'ranks',
you'll see performance degradation. But that's in terms of clock speed,
not in disabling triple channel.

But as said, that all depends on the memory controller in the server's
mainboard or processors.

Best regards,

Arjen

pgsql-performance by date:

Previous
From: Claudio Freire
Date:
Subject: Re: Adding more memory = hugh cpu load [solved]
Next
From: Claudio Freire
Date:
Subject: Re: Adding more memory = hugh cpu load [solved]