On Fri, Feb 05, 2016 at 12:27:25PM -0800, Greg Kroah-Hartman wrote:
> > This goes back to 23MB/s (size/time), which is proper speed.
> > I also verified that this time the LED wasn't flashing after unmount.
>
> Great, so all is good now?
>
> > > Still, it's a more appropriate value, indicating that the actual
> > > transfer speed is reasonably close to what it should be.
> >
> > Correct. There seems to be a problem between sync and the underlying
> > usb-storage driver?
> > Maybe the windows driver takes many packets at a time, and returns sync
> > for a bunch of them while linux syncs them one by one, which ends up
> > being 50 times slower.
>
> That's up to the filesystem layer, what it wants to do, not the
> usb-storage driver.
Understood.
> So you get to go poke your favorite distro about this, it's not
> something the kernel can do much, if anything, about. :)
The thing is async isn't great either.
I hate to say, but windows does this right, linux does not as far as I
can tell.
When a windows copy is finished, it's pretty much on flash (maybe with a
second delay)
On linux, it is if I accept a speed that 50x slower, or it's not and
data is lost if I pull my usb device after the copy is over without
unmount (I have automatic mount).
In other words, with linux, the copy either finishes way before it's on
flash, or takes many times longer.
However, I agree that apparently the usb layer is apparently not the
place that can fix it.
I also understant that this problem has been there for as long as USB
devices have existed, so if it hasn't been fixed in a better way by now,
it's likely not trivial.
Either way thanks all for the answers.
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/ | PGP 1024R/763BE901
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