Date: Wed, 4 Mar 2009 14:37:58 -0800 From: Steve Calfee <stevecalfee@gmail.com> To: Hans Petter Selasky <hselasky@c2i.net> Cc: freebsd-usb@freebsd.org Subject: Re: Low perfomance when read from usb flash drive Message-ID: <4a5ff6bc0903041437l52a58387v1735e34ebc383847@mail.gmail.com> In-Reply-To: <200903042311.00403.hselasky@c2i.net> References: <200903010045.44904.man@email.com.ua> <200903030850.01866.hselasky@c2i.net> <200903041047.57385.man@email.com.ua> <200903042311.00403.hselasky@c2i.net>
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On Wed, Mar 4, 2009 at 2:10 PM, Hans Petter Selasky <hselasky@c2i.net> wrote: > On Wednesday 04 March 2009, Artyom Mirgorodsky wrote: >> I forgot to write, that a similar problem was observed in FreeBSD 7 with >> usb4bsd patches. > > Here is a patch which I think will address your problem. It is EHCI hardware > related. Different models behave differently. Try this: > > http://perforce.freebsd.org/chv.cgi?CH=158692 > Wow, that is bizarre. The "doorbell" is usually used so the software knows that the cpu vs dma race is complete when moving qtds off the qh - ie dequeueing requests. What you have done is asked the guy doing the photo finish at the end of a horse race to press the shutter a little before the horse crosses the line - so the shutter latency will allow a picture right as the horse crosses the line. Unfortunately, this (like all races) is affected by the object doing the racing - horse speed and camera speed are variable! I believe something else must be wrong. Regards, Steve
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