Date: Fri, 19 Mar 2010 11:29:53 +0100 From: Bernd Walter <ticso@cicely7.cicely.de> To: Sebastian Huber <sebastian.huber@embedded-brains.de> Cc: Bernd Walter <ticso@cicely7.cicely.de>, ticso@cicely.de, freebsd-usb@freebsd.org Subject: Re: How fast is the OHCI driver? Message-ID: <20100319102953.GO83844@cicely7.cicely.de> In-Reply-To: <4BA344C3.2010901@embedded-brains.de> References: <4B9FA7CB.70200@embedded-brains.de> <20100316180109.GE70566@cicely7.cicely.de> <4BA344C3.2010901@embedded-brains.de>
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On Fri, Mar 19, 2010 at 10:32:51AM +0100, Sebastian Huber wrote: > On 03/16/2010 07:01 PM, Bernd Walter wrote: > > On Tue, Mar 16, 2010 at 04:46:19PM +0100, Sebastian Huber wrote: > [...] > >> Has someone values from other FreeBSD based systems with an OHCI controller? > > > > I can easily get more with AT91RM9200 (also ARM9 with OHCI). > > A short test: > > [73]chipmunk.cicely.de# dd if=/dev/da0 bs=128k of=/dev/null count=100 > > 100+0 records in > > 100+0 records out > > 13107200 bytes transferred in 16.762732 secs (781925 bytes/sec) > > > > Speedwise the system is on the lowest end of ARM9 systems we support. > > > > Thank you for your reference values. Actually my test setup on the FreeBSD > based system was bad. I now have the following values: > > TSZ: Size of one transfer block in bytes > TIME: Time to transfer 1024 blocks in seconds > RATE: Bytes transfered per second > > TSZ TIME RATE > 512 6.15 85250 > 1024 7.17 146244 > 2048 8.20 255750 > 4096 10.24 409600 > 8192 13.38 626951 > 16384 21.50 780335 > 32768 36.92 908841 > 65536 67.92 988057 > 131072 131.39 1021521 > 262144 259.00 1036430 > 524288 514.16 1044170 > 1048576 964.04 1048532 > > So it looks very good if you use the right transfer size. That's normal - Linux uses block devices, which prereads bigger blocks, while we have character devices and have physical control. The story isn't a problem if you use a filesystem, because it does bigger reads. The consumer code likely knows better what is worth to be preread and/or cached. -- B.Walter <bernd@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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