Hi, If you want to get rid of the Kernel IPI interrupts you can disable one of the cores in the BIOS. Doing this I can get an amazing 3 wake ups per second in PowerTOP on a fully functional Gnome Desktop (Intel Core 1 Duo). Of course you will lose some performance depending on the kind of workload you run on your laptop.
The funny thing is that I don't have to do this on an Intel Core 2 Quad Desktop. Even with four cores Kernel IPI interrupts barely show up in powertop (Only when there is high load). Why is that? Maybe the scheduler in the kernel can be improved to handle the Core 1 Duo architecture better, I don't know. Regards, -William --- El jue 8-ene-09, Peter F. Patel-Schneider <[email protected]> escribió: De:: Peter F. Patel-Schneider <[email protected]> Asunto: misleading information from powertop related to rescheduling interrupts A: [email protected] Fecha: jueves, 8 enero, 2009, 7:46 am Hi: I've been thinking about how rescheduling interrupts *might* work in Linux and how they relate to powertop's reporting. First, a caveat: I don't understand very much about either Linux kernel internals or Intel hardware. It seems to me that on *some* hardware, a kernel IPI resulting from rescheduling interrupts shouldn't have any power implications. Consider a Thinkpad T60, which has a twin-code processor. I believe that with this hardware both processors always run at the same speed. This means that running one processor is almost as energy-intensive as running two processors. Since rescheduling interrupts just starts the "idle" processor, almost certainly while the other processor is working, rescheduling interrupts should be in this very-cheap situation. So, given all that, maybe powertop shouldn't be reporting rescheduling interrupts (and thus causing lots of angst) for such hardware. Perhaps powertop could do this in general - not reporting events that don't cost energy. Of course this all depends on whether my analysis is correct. Comments? Peter F. Patel-Schneider PS: Of course, it is still mystifying that rescheduling interrupts can cause more than 50% of wakeups, or even a significant fraction of wakeups with an extremely light load. How can it make sense to wakeup the other core when all the current core is doing is finishing the work needed to service an interrupt. _______________________________________________ Power mailing list [email protected] http://www.bughost.org/mailman/listinfo/power ¡Todo sobre Amor y Sexo! La guía completa para tu vida en Mujer de Hoy. http://mx.mujer.yahoo.com/ _______________________________________________ Power mailing list [email protected] http://www.bughost.org/mailman/listinfo/power
