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 = 0; tout.tv_usec = 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=2314#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 r...@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 _______________________________________________ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "freebsd-usb-unsubscr...@freebsd.org"