On 04/30/2015 11:31 PM, Alan Stern wrote:
>On Thu, Apr 30, 2015 at 12:37:15AM -0500, Felipe Balbi wrote:
> >On Thu, Apr 30, 2015 at 10:46:51AM +0800, Xuebing Wang wrote:
> > >
> > >On 04/30/2015 12:45 AM, Felipe Balbi wrote:
> > > >>>try setting nofua parameter. Windows always sets FUA bit (so all writes
> > > >>>> >are*always* flushed to non-volatile media), but telling mass storage
> > > >>>> >gadget to ignore FUA bit, you get better performance.
> > > >>>
> > > >>>At the expense of possibly loosing your data if you loose power, so
> > > >>>ignore it at your own peril:)
> > > >Well, unless you're completely powered via USB and have no batteries,
> > > >then yeah, you have an issue. The likelyhood that you have batteries is
> > > >much, much larger, though.
> > >
> > >Thanks for the help. However, enable nofua seems not helping performance
> > >with Win7 host. My command is:
> > >modprobe g_mass_storage file=/dev/mmcblk0p4 removable=1 nofua=1
> >
> >then you're really on your own. I would suggest a sniffer to figure out
> >if the host isn't sending tokens fast enough (too many SOFs) or the
> >device isn't fast enough (too many NAKs/NYETs).
Even without a hardware sniffer, it is possible to get useful timing
information by uncommenting the
/* #define VERBOSE_DEBUG */
/* #define DUMP_MSGS */
lines near the start of f_mass_storage.c.
It's also worth mentioning that you are never supposed to use
g_mass_storage without specifying a serial number string. This may not
affect the transfer rates, but I know that Windows does pay attention
to the serial number string.
Alan Stern
>oh yeah, if you can reproduce the same thing using a recent kernel
>(v4.0, for example) and give us further details of your setup (which
>platform, which controller you're using, etc), then linux-usb will be
>very happy to help out.
Felipe, Alan,
Thanks for the help. Yes, I can reproduce this issue with kernel v4.0.1
on our own board which is similar to Freescale iMX6SL EVK (evaluation
board).
Command is : modprobe g_mass_storage file=/dev/mmcblk0p4 removable=1 nofua=1
For copying 180MB file from host to device:
-- At Win7 host, it takes about 60 seconds to copy. After GUI finishes
copying at Win7, and type "sync" at device side, "sync" returns immediately.
-- At MacOS host, it takes about 15 seconds for GUI to finishes copying.
After GUI finishes copying, type "sync" at device side, "sync" takes
about 10 seconds to return.
-- Ubuntu 14.04.1 host performance is similar to MacOS.
Likely, this is not related to SoC platform or eMMC, what do you think?
Thanks for your willingness to help. Would you mind to do quick test on
your hardware platform (e.g. TI SoC) if you have a Windows host?
Xuebing
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