On Tue, Apr 20, 2004 at 11:42:41AM -0400, Alan Stern wrote:
> Greg:
> 
> Following a suggestion of David Brownell's I have decided to remove
> support for the URB_NO_INTERRUPT flag in the UHCI driver.  The overall
> effect of the flag is to reduce the number of interrupts, thereby
> improving throughput somewhat while increasing the duration of the
> remaining IRQ handlers quite a lot (i.e., increasing interrupt variance).  
> So I think we're better off without it.  Mind you, this is all in the
> absence of any firm measurements.
> 
> A common case where this will come up is during usb-storage bulk
> transfers.  Such transfers are generally divided into scatter-gather
> components each corresponding to a single URB and transferring one memory
> page (4 KB).  While generating an interrupt for each one is a little
> faster than ideal -- about every 3 ms -- it's better than waiting until 64
> KB has been transferred and there are 1024 individual TDs to clean up
> during the IRQ.
> 
> Please apply.

Applied, thanks.

greg k-h


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