[Discuss] USB speeds

[gaf at blu.org (Jerry Feldman)]

I noticed the other day that when I copied an Android image to my
microSD, using dd on my home system it took a lot longer than on
Windows. lspci indicates that the USB is a USB 2.
Since my work is closed today, I don't have access to the Windows
machine. I plan to boot a live cd with a recent kernel and time a dd
compared to using Windows XP so I have some real numbers.
My home system has
[gaf at gaf ~]$ lspci -v | grep USB
00:02.0 USB Controller: nVidia Corporation MCP55 USB Controller (rev a1)
(prog-if 10 [OHCI])
00:02.1 USB Controller: nVidia Corporation MCP55 USB Controller (rev a2)
(prog-if 20 [EHCI])

my command was dd if=<image> of=/dev/sdd
This is what dmesg gives me when I insert a thumb drive. (my uSD is
currently inthe Nook).
[ 4825.079042] usb 1-3: new high speed USB device number 7 using ehci_hcd
[ 4825.198115] usb 1-3: New USB device found, idVendor=13fe, idProduct=3600
[ 4825.198123] usb 1-3: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[ 4825.198130] usb 1-3: Product: USB DISK Pro
[ 4825.198134] usb 1-3: Manufacturer:        
[ 4825.198138] usb 1-3: SerialNumber: 90B30B00E94F14DB
[ 4825.376616] usbcore: registered new interface driver uas
[ 4825.388935] Initializing USB Mass Storage driver...
[ 4825.389272] scsi8 : usb-storage 1-3:1.0
[ 4825.389543] usbcore: registered new interface driver usb-storage
[ 4825.389549] USB Mass Storage support registered.
[ 4826.413295] scsi 8:0:0:0: Direct-Access              USB DISK Pro    
PMAP PQ: 0 ANSI: 0 CCS
[ 4826.416670] sd 8:0:0:0: Attached scsi generic sg5 type 0
[ 4828.434176] sd 8:0:0:0: [sdd] 7833600 512-byte logical blocks: (4.01
GB/3.73 GiB)
[ 4828.436292] sd 8:0:0:0: [sdd] Write Protect is off
[ 4828.436299] sd 8:0:0:0: [sdd] Mode Sense: 23 00 00 00
[ 4828.438290] sd 8:0:0:0: [sdd] No Caching mode page present
[ 4828.438296] sd 8:0:0:0: [sdd] Assuming drive cache: write through
[ 4828.445292] sd 8:0:0:0: [sdd] No Caching mode page present
[ 4828.445300] sd 8:0:0:0: [sdd] Assuming drive cache: write through
[ 4828.462936]  sdd: sdd1 sdd4
[ 4828.469297] sd 8:0:0:0: [sdd] No Caching mode page present
[ 4828.469305] sd 8:0:0:0: [sdd] Assuming drive cache: write through

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
PGP key id:3BC1EB90 
PGP Key fingerprint: 49E2 C52A FC5A A31F 8D66  C0AF 7CEA 30FC 3BC1 EB90