Re: Accelerating Linux software raid

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).