Date: Thu, 20 Jan 2011 17:04:25 +1030 From: "Daniel O'Connor" <darius@dons.net.au> To: freebsd-usb@freebsd.org Subject: libusb performance on 8.1 Message-ID: <2B69A13C-72BF-4F73-9216-BBAFE3C83B94@dons.net.au>
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Hi,
I am building a USB interface to a radar data acquisition chassis based =
on the Cypress CY7C68013A.
While doing some speed testing I find that FreeBSD does ~4Mb/sec, but =
Linux does 17Mb/sec & OS X does 8-10Mb/sec.
It is using libusb-1.0 with the async API in a threaded app. I spawn a =
thread which sites in the following loop:
while (!child_exit) {
tout.tv_sec =3D 0;
tout.tv_usec =3D 100000;
libusb_handle_events_timeout(ctx, &tout);
}
ugsio_cancelusb();
The parent thread is the rest of the program which and handles reading =
data out of the completed transfers and forwarding them to the data =
processing children and re-submitting them to the USB stack.
I keep 8 transactions of 512 bytes each in flight. The device itself =
holds up to 4 packets in a FIFO until the PC is ready. Increasing the =
number of transactions in flight has no effect on performance.
Does anyone have a suggestion as to how I can look at improving =
performance? Deploying Linux is not really an option :)
The Linux PC is..
Linux fpgawork 2.6.32-28-generic #55-Ubuntu SMP Mon Jan 10 23:42:43 UTC =
2011 x86_64 GNU/Linux
The CPU is a Core 2 E6400 @ 2.13GHz on a Gigabyte 965P-DS3 rev 1 =
(http://www.gigabyte.com/products/product-page.aspx?pid=3D2314#ov) which =
has an ICH8 chipset.
The FreeBSD PC is..
FreeBSD aumond8.gsoft.com.au 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Jul =
19 02:55:53 UTC 2010 =
root@almeida.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC i386
The CPU is a Core 2 E7500 @ 2.93GHz on a Supermicro C2SBA+ =
(http://www.supermicro.com/products/motherboard/Core/G33/C2SBA_.cfm) =
which has an ICH9 chipset.
Any patches welcome!
Thanks.
--
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
-- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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