[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <Y0XJzGW/zlcCfffi@kroah.com>
Date: Tue, 11 Oct 2022 21:53:48 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Michael Grzeschik <mgr@...gutronix.de>
Cc: Dan Vacura <w36195@...orola.com>, linux-usb@...r.kernel.org,
Daniel Scally <dan.scally@...asonboard.com>,
Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
Jonathan Corbet <corbet@....net>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Felipe Balbi <balbi@...nel.org>,
Paul Elder <paul.elder@...asonboard.com>,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 0/3] uvc gadget performance issues
On Tue, Oct 11, 2022 at 09:48:08PM +0200, Michael Grzeschik wrote:
> I also have an patch in the queue that will limit the sg support for
> devices with speed > HIGH_SPEED. Because of the overhead of the limited
> transfer payload of 1024*3 Bytes, it is possible that a simple memcpy
> will actually be fast enough. But for that patch I still have to make
> proper measurements. Btw. which USB speed are you transferring with?
For a payload that small, yes a memcpy is almost always faster. I think
it's only much larger sizes that actually start to help with sg.
Can you submit this change now? Odds are it will help out a lot of
systems.
thanks,
greg k-h
Powered by blists - more mailing lists