[gentoo-user] Re: [OT] Disappointing USB3 performance

[walt <w41ter@gmail.com>]

On 10/24/2011 10:28 AM, walt wrote:
> ...
> Over at least six trials on each docking station I consistently
> get 105 seconds for USB and 84 seconds for e-sata, a 5:4 ratio
> in favor of e-sata/sata over USB3/sata...

Wow, lots of great answers, guys, thanks.  Enough material to give
me lots more questions to ask you :)

Like, for example, in theory the raw bit-rate for USB3 is more than
enough to keep up with any existing consumer hard drive, right?  The
speed of usb/sata protocol translation should be very fast compared
to the speed of a spinning mechanical disk (I think?)

Now, lack of DMA is another story for hard disks, certainly.  Here's
where my ignorance of hardware limits my thinking:

AFAIK the device driver *always* sits between the disk drive and the
DMA hardware, doesn't it?

Seems to me that the USB3 driver should be fast enough to shuttle the
raw disk data (somehow) to the DMA hardware just like the pata/sata
drivers do.  It's that "somehow" that I obviously don't understand.

Where am I thinking wrong about the problem?