RE: cygwin copy problems usb 2.0

["Gary R. Van Sickle" <g dot r dot vansickle at worldnet dot att dot net>]

> From: aldana
> Sent: Thursday, July 27, 2006 7:15 AM
> Subject: cygwin copy problems usb 2.0
> 
> 
> hi,
> 
> i've got usb 2.0, when i copy through TotalCommander the copy 
> speed is quite high.

I have no idea what a TotalCommander is, but from the context here I assume
it's a native Windows app that has copying abilities which are highly
optimized for speed.

> when i copy through cygwin shell it 
> seems that it is transmitting data only with usb 1.x speed. 
> very spooky, because i thought that cygwin is calling windows 
> drivers/api so it should be indirectly supporting usb2.0 ?
> 

I can assure you with 99.44% confidence that Cygwin is not somehow
downgrading your USB connections from 2.0 to 1.x.  Such decisions get made
at a much much lower level than user-mode apps operate at.  In fact, I doubt
it's even possible for this to happen in kernel-mode code - I think this all
happens at the hub/device hardware/SIE level.

Cygwin's cp is slower than a native copy, from anywhere to anywhere else,
for a number of reasons.  The main one, last I looked (admittedly years
ago), was a fallout of portability.  Cp opens file and copies them an
(f)read/(f)write buffer at a time, while your Windows native program almost
certainly simply calls CopyFile() (a Win32 API), bypassing a ton of library
code.

-- 
Gary R. Van Sickle
 


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