On Thu, 30 Apr 2015, Felipe Balbi 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. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
