Low perfomance when read from usb flash drive

[Hans Petter Selasky]

On Monday 02 March 2009, Artyom Mirgorodsky wrote:
> > It might be a bug with your memory stick. Are your findings consistent
> > accross other brands of memory sticks aswell, between 7.1 and 8.x ?
>
> Today, I tested another flash drive
>
> ugen1.2: <USB 2.0> at usbus1
> umass0: <BUCK> on usbus1
> umass0:  SCSI over Bulk-Only; quirks = 0x0000
> umass0:3:0:-1: Attached to scbus3
> sg1 at umass-sim0 bus 0 target 0 lun 0
> sg1: <USB 2.0 Flash Disk 1.00> Removable Direct Access SCSI-2 device
> sg1: 40.000MB/s transfers
> pass1 at umass-sim0 bus 0 target 0 lun 0
> pass1: <USB 2.0 Flash Disk 1.00> Removable Direct Access SCSI-2 device
> pass1: 40.000MB/s transfers
> GEOM: new disk da0
> da0 at umass-sim0 bus 0 target 0 lun 0
> da0: <USB 2.0 Flash Disk 1.00> Removable Direct Access SCSI-2 device
> da0: 40.000MB/s transfers
> da0: 3872MB (7929856 512 byte sectors: 255H 63S/T 493C)
>
>
>
> FreeBSD-8-Current
>
> dd if=/dev/da0 of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 60.320972 secs (10864546 bytes/sec)
>
> systat -vm
>
> Disks   ad4   ad6   da0   cd0 pass0   sg0   sg1     68560 wire
> KB/t   0.00  0.00 64.00  0.00  0.00  0.00  0.00    117684 act
> tps       0     0   166     0     0     0     0     75468 inact
> MB/s   0.00  0.00 10.40  0.00  0.00  0.00  0.00      1860 cache
> %busy     0     0    99     0     0     0     0   1136340 free
>
>
>
> FreeBSD-7.1
>
> dd if=/dev/da0 of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 44.021160 secs (14887386 bytes/sec)

Hi,

What brand is your CPU.

I know that certain AMD USB controllers perform less with the new USB stack, 
but I've not been able to track down the issue.

Can you try another PC having another CPU brand?

There might be some minor things that needs tuning like the NAK retry counter. 
I suspect you have run into a timing issue with the hardware.

--HPS