On Wed, 2006-27-12 at 14:08 +0100, Arjan van de Ven wrote: > sure; however the kernel doesn't provide more accurate information > currently (and I doubt it could even, it's not so easy to figure out > which interface triggered the softirq if 2 interfaces share the cpu, and > then, how much work came from which etc). >
If you sample CPU use and in between two samples you are able to know which nic is tied to which CPU, how much cycles such cpu consumed in user vs kernel, and how many packets were seen on such nic; then you should have the info necessary to make a decision, no? Yes, I know it is a handwave on my part and it is complex but by the same token, I would suspect each kind of IO derived work (which results in interupts) will have more inputs that could help you make a proper decision than a mere glance of the interupts. I understand for example the SCSI subsystem these days behaves very much like NAPI. I think one of the failures of the APIC load balancing is a direct result of not being able to factor in such enviromental factors. > also the "amount of work" estimate doesn't need to be accurate to 5 > digits to be honest... just number of packets seems to be a quite > reasonable approximation already. (if the kernel starts exporting more > accurate data, irqbalance can easily use it of course) It is certainly much more promising now than before. Most people will probably have symettrical type of apps, so it should work for them. For someone like myself i will still not use it because i typically dont have symettrical loads. cheers, jamal - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
