Re: The performance and behaviour of the anti-fragmentation relatedpatches

[Andrew Morton]

On Fri, 2 Mar 2007 09:35:27 -0800
Mark Gross <mgross@xxxxxxxxxxxxxxx> 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.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/