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[Discuss-gnuradio] USB2 host controller performance

From: Eric Blossom
Subject: [Discuss-gnuradio] USB2 host controller performance
Date: Thu, 18 Dec 2003 07:55:59 -0800
User-agent: Mutt/1.4.1i

The highest performing USB2 host controller we've found so far is the
Intel 82801DB.  It's built into either the north or south bridge and
is the one where we can sustain 31.25 MB/sec in either direction.
We've seen this controller in an IBM X31 notebook.

lspci gives this info:

00:1d.0 USB Controller: Intel Corp. 82801DB USB (Hub #1) (rev 01)
00:1d.1 USB Controller: Intel Corp. 82801DB USB (Hub #2) (rev 01)
00:1d.2 USB Controller: Intel Corp. 82801DB USB (Hub #3) (rev 01)
00:1d.7 USB Controller: Intel Corp. 82801DB USB2 (rev 01)

On the PCMCIA front, Matt has tested about 7 or 8 cards, allegedly
from different vendors.  Despite the different packaging and labels,
they all have had the same guts.  They identify in usbview as "PCI
Device 1033:00e0" and they all pretty much suck for throughput.  The
DLINK card was the cheapest of the bunch.  Checking pci.ids indicates
that 1033:00e0 is an NEC USB 2.0 Root hub.

In the transmit direction, they'll sustain 7.8 MB/sec; on the receive
path, 15.625 MB/sec.  We didn't do extensive testing.  It's possible
we missed something.

I have heard that the NEC chip doesn't talk on both the PCI bus and
the USB at the same time.  This explains the low throughput, but not
the asymmetry between Rx and Tx.

If you've got other host controller data, please post it.


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