Messages in this thread | | | Subject | Re: [Q]: Linux and real device drivers | From | Jes Sorensen <> | Date | 23 Sep 1999 09:50:28 +0200 |
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>>>>> "Steve" == Steve Underwood <steveu@infowebtelecom.com> writes:
Steve> Jes Sorensen wrote: Jamie> A card that can be told "don't interrupt me for N us after Jamie> receiving the next packet, unless you hit the high water mark" Jamie> would be even better. >> Thats exactly what some Gigabit Ethernet cards do.
Steve> A number of newer devices do this. It has benefits, but it has Steve> a downside too. It imposes significant extra latency when there Steve> is just a light load, which can hurt performance on Steve> transactional traffic. A better scheme might be more like the Steve> 16550 UART. Interrupt if you hit the high tide point, or the Steve> wire goes quiet for a short while. Short here can mean very Steve> short. This gives more interrupts under light load, when you Steve> probably have plenty of spare CPU cycles to deal them. When the Steve> load increases the interrupt rate drops. I haven't seen an Steve> Ethernet chip which works in that way, but then I haven't Steve> studied them all.
Thats exactly the situation Jamie explained, there is no difference.
Jes
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