Date: Tue, 16 Mar 2010 22:46:40 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-usb@freebsd.org Subject: Re: How fast is the OHCI driver? Message-ID: <201003162246.40130.hselasky@c2i.net> In-Reply-To: <4B9FA7CB.70200@embedded-brains.de> References: <4B9FA7CB.70200@embedded-brains.de>
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On Tuesday 16 March 2010 16:46:19 Sebastian Huber wrote: > Hi, > > I work with an ARM9 based system on a LPC3250 evaluation board from Phytec. > It has an integrated OHCI USB controller from NXP. The vendor provides a > Linux system for this board and with this system I can read with 1MByte/s > from an USB stick (I can also read with 23MByte/s from this stick on > another system with an EHCI controller). If I use the FreeBSD USB-stack > (trunk revision 200101), then I can only achieve a read performance of > 70kByte/s. Comparing the activity on the USB data lines with an > oscilloscope of the two systems shows that on the Linux system the line is > continuously busy while on the FreeBSD based system there are huge gaps of > inactivity. Both systems operate with 12MHz. The FreeBSD based system is > 65% of the time in the idle task, so it seems that it waits a lot for > something. > > Has someone values from other FreeBSD based systems with an OHCI > controller? > > Have a nice day! > Sebastian Huber > Hi, This might be a symptom of the well known cache flush/sync problem. You should investigate whether all transfer descriptors get flushed/invalidated correctly to RAM after setting up an USB transaction. There are sysctl under hw.usb.xxx where you can enable more verbose debugging. --HPS
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