Re: Accelerating Linux software raid

[Ric Wheeler <ric@emc.com>]

Konstantin Olchanski wrote:

>I am now confused. Is somebody trying to save power by adding an i/o
>coprocessor? (with it's own power overhead for memory, i/o, etc)
>
>To me it is simple:
>
>1) If you have an infinite power budget (big box), you might as well
>   let the main cpus do the raid stuff. If you are short on power (embedded),
>   you cannot afford to power an extra processor (+memory and stuff).
>
>2) If you have rich customers (big box), let them pay for a bigger
>   main cpu to do the raid, if you want to be cheap (embedded, appliance),
>   you cannot afford to plop an extra cpu (+support chips) on your custom pcb.
>  
>
The actual facts don't support this view since the gap in power 
consumption is huge. Most of these system on a chip designs provide the 
main CPU/northbridge/southbridge and extra execution units for a small 
fraction of one standard CPU.  Say under 20  watts for all of the above 
versus up to (over sometimes) 100 watts for a standard CPU (without its 
system chip sets).