[U-Boot] usb_test_unit_ready called every block read - performance

Jim Shimer
2012-08-15T14:19:45Z

Hi Marek,

I looked at the ext4 branch. It looks like he has the patch to remove the
usb_test_unit_ready() calls which were not needed. Actually those calls are
commented out on that branch:
#if 0
if (usb_test_unit_ready(srb, ss)) {
printf("Device NOT ready\n Request Sense returned %02X
%02X"
" %02X\n", srb->sense_buf[2], srb->sense_buf[12],
srb->sense_buf[13]);
return 0;
}
#endif

In the u-boot-usb.git, this code is removed so at some point there will be
a merge conflict.

Also the ext4 branch still has the mdelay(5) always being done in
usb_stor_BBB_transport() line 696 which we found to be the largest
performance killer.

Regards,
Jim

On Sun, Aug 12, 2012 at 7:54 PM, Marek Vasut <marex@denx.de> wrote:

> Dear Jim Shimer,
>
> > While tuning ext2load, we found that usb_test_unit_ready was being called
> > every block read. We compared the usb block storage to the scsi block
> > storage cmd_scsi.c, and found that the scsi device was only calling its
> > scsi_setup_test_unit_ready() during scsi_can. It appears that
> > usb_test_unit_ready() really only needs to be called once during
> > usb_stor_scan(), via usb_stor_get_info(). Is there a particular reason
> > usb_test_unit_ready is called for every block read, or do you think its
> ok
> > to only call during usb_stor_scan()? We're finding this speeds up
> ext2load
> > quite a bit.
>
> Jim, did we get anywhere on this one ? Can you try with the new ext4 code
> in
> Wolfgangs' u-boot-master/ext4 branch?
>
> > Regards,
> > Jim
>
> Best regards,
> Marek Vasut
>

--
*James H Shimer*
Motorola Mobility T3-12-HH72
900 Chelmsford Street
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