Date: Thu, 5 Mar 2009 09:48:39 +0900 From: "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au> To: freebsd-usb@freebsd.org Subject: Re: Low perfomance when read from usb flash drive Message-ID: <20090305004839.GH92789@stlux503.dsto.defence.gov.au> In-Reply-To: <200903050009.48188.hselasky@c2i.net> References: <200903010045.44904.man@email.com.ua> <200903042311.00403.hselasky@c2i.net> <4a5ff6bc0903041437l52a58387v1735e34ebc383847@mail.gmail.com> <200903050009.48188.hselasky@c2i.net>
next in thread | previous in thread | raw e-mail | index | archive | help
Excuse my ignorance, but what is meant by "doorbell" ?
-aW
0n Thu, Mar 05, 2009 at 12:09:47AM +0100, Hans Petter Selasky wrote:
>The new USB stack _is_ doing things faster than the old one. I have gone
>through a large range of tests before I landed on the doorbell trick.
>Actually the new USB stack doesn't use the doorbell, we use software timers
>instead. The hardware certainly behaves different from vendor to vendor.
>Probably somone making the chips have to explain what is wrong.
>
>In my (Nvidia+AMD64+EHCI) test case I tried:
>
>No doorbell: 12 Mbyte/sec
>Doorbell after transfer (after QH removal): 14 Mbyte/sec
>Doorbell after next transfer (after QH insertion): 21 Mbyte/sec
IMPORTANT: This email remains the property of the Australian Defence Organisation and is subject to the jurisdiction of section 70 of the CRIMES ACT 1914. If you have received this email in error, you are requested to contact the sender and delete the email.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20090305004839.GH92789>