Thread (47 messages) 47 messages, 10 authors, 2007-08-05

Re: serial flow control appears broken

From: Maciej W. Rozycki <hidden>
Date: 2007-07-30 09:45:31
Also in: lkml

Possibly related (same subject, not in this thread)

On Sat, 28 Jul 2007, Russell King wrote:
Essentially, any complex interrupt handler (such as an IDE interrupt
doing a multi-sector PIO transfer _in interrupt context_) can cause this
kind of starvation.  That's why Linux 1.x had bottom halves - so that
the time consuming work could be moved out of the interrupt handler,
thereby causing minimal the blockage of other interrupts.

Unfortunately, that kind of design has been long since forgotten.
Apparantly modern machines are fast enough that it doesn't have to be
worried about anymore...  Or are they?
 I would guess it is not that the machines are fast enough, but that this 
two-level processing makes things more complicated.  Enough that most 
people would not bother digging into it unless really forced.  Only 
occasional latency problems are probably not enough of a force.

  Maciej
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