On Tue, 9 Nov 2004 [EMAIL PROTECTED] wrote:

> > I don't understand what you're asking.  How is the operating system
> > supposed to respond to a READ operation when the device refuses to send
> > the data, except by telling the program that an error occurred?
> 
> Well, actually I don't know. I see that under Windows there must be some kind 
> of
> retry mechanism. The disk/controller/whatever signals an error, this error is
> recorded in the event log and afterwards some kind of retry occurs. In the
> result the correct buffer seems to be available for the application requesting
> it.
> 
> Here is my procedure in detail: I created >20G of 1M files. Every file 
> contains
> the same pattern: bytes from 0-255 in accending order. A second program tried
> to read these files sequentially and non-concurrently to the writer. Finally, 
> I
> compared the result from the disk with the expected. With this test I see that
> Linux forwards the error to the application and that Windows has some kind of
> retry mechanism. My question is: is it possible to implement such a retry
> mechanism within the Linux USB subsystem?

There already is such a mechanism.  Requests are retried multiple times.

Alan Stern



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