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

From Claudio Freire
Subject Re: Adding more memory = hugh cpu load [solved]
Date
Msg-id CAGTBQpb4-5V+r+feNRHc-SQYNetujC0HgsnHZ3v-WnNHZirFTA@mail.gmail.com
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In response to Re: Adding more memory = hugh cpu load [solved]  (Arjen van der Meijden <acmmailing@tweakers.net>)
List pgsql-performance
On Tue, Oct 11, 2011 at 5:33 PM, Arjen van der Meijden
<acmmailing@tweakers.net> wrote:
> 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.
>

There are too many caveats to doing that, including how they're
installed (in which slots), the timings, brand, internal structure,
and whatnot, with all those details not always published, only sitting
in the module's SPD.

In essence, mixing is more probable to mess your multichannel
configuration than not.

That's why matched kits are sold.

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