Re: [PATCH v2] Add support for usbfs zerocopy.

From: Lingzhu Xiang
Date: Fri Jan 08 2016 - 23:17:21 EST

On Wed, Nov 25, 2015 at 7:19 PM, Steinar H. Gunderson <sesse@xxxxxxxxxx> wrote:
> Add a new interface for userspace to preallocate memory that can be
> used with usbfs. This gives two primary benefits:

Extended testing over one hour shows significant improved CPU usage
and stability:
The old CPU usage is about 12% +/- 5%. The new CPU usage is 4% +/- 1%.

The setup is an i7-4600U laptop running Kinect v2 with 260MB/s
isochronous and 20MB/s bulk transfers.

The improvement in reducing jitter is particularly preferable to
Kinect v2 driver because the isochronous data is structured and one
packet lost means discarding a lot of data.