On Wed, Sep 06, 2006 at 11:10:14AM -0600, Eric W. Biederman wrote: > There is fundamentally more work to do when you take an interrupt because > you need to take a context switch. But cost of a context switch is in > the order of microseconds, so while measurable taking an interrupt should > not dramatically your latency numbers.
Unless, of course, your latency is a microsecond. In fact, our *overhead* for a single message is much less than 1 usec, so an interrupt per message would kill our message rate. And, finally, all the cpus can poll main memory in an embarrassingly parallel fashion, whereas interrupts involve OS contention. > This is important as polling for new packets has a very significant > opportunity > cost as it prevents you from get any other work done at the same time In most codes, the opportunity cost of polling is zero. But I can only speak from my experience, do you have any data which shows different? -- greg _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
