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). -- balbi
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