Re: The performance and behaviour of the anti-fragmentation related patches

Andrew Morton
2007-03-02T18:10:40Z

On Fri, 2 Mar 2007 09:35:27 -0800
Mark Gross <mgross@linux.intel.com> wrote:

> >
> > Will it be possible to just power the DIMMs off? I don't see much point in
> > some half-power non-destructive mode.
>
> I think so, but need to double check with the HW folks.
>
> Technically, the dims could be powered off, and put into 2 different low
> power non-destructive states. (standby and suspend), but putting them
> in a low power non-destructive mode has much less latency and provides
> good bang for the buck or LOC change needed to make work.
>
> Which lower power mode an application chooses will depend on latency
> tolerances of the app. For the POC activities we are looking at we are
> targeting the lower latency option, but that doesn't lock out folks from
> trying to do something with the other options.
>

If we don't evacuate all live data from all of the DIMM, we'll never be
able to power the thing down in many situations.

Given that we _have_ emptied the DIMM, we can just turn it off. And
refilling it will be slow - often just disk speed.

So I don't see a useful use-case for non-destructive states.