Re: Kernel preemption, yes or no? (was: Filesystem gets a hugeperformance boost)

[E.B. Dreger]

> Date: Wed, 18 Apr 2001 00:04:12 -0300 (BRST)
> From: Rik van Riel <[EMAIL PROTECTED]>
> 
> Not true. Interrupts work worse than polling because the interrupt
> top halves can keep the CPU busy, whereas with polling you only

Top halves and _task switching_.  Again, in a well-written handler with a
tight loop, task switching becomes expensive.

> peek at the card when you have time.

Think aio_xxxx versus kernel queues. :-)

> This means pure interrupts can possibly DoS a CPU (think about a
> gigabit ping flood) while polling leaves the box alive and still
> allows it to process as much as it can (while not wasting CPU on
> taking in packets it cannot process higher up the stack).

I should hope that the card would be smart enough to combine consecutive
packets into a single DMA transfer, but I know what you mean.


Eddy

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