kernel coder writes: > I'm doing trying to write some optimized code for AMD dual core > opetron processor.But things are getting no where.I've installed > Fedora 5 with 2.6 series Linux kernel and 4 series GCC > > Following are few lines of code which are consuming close to 100 > cycles.Yes this is not the forum for such questions but i think people > on linux kernel and GCC are best to answer such type of questions.I'm > realy getting frustated and helpless ,that's why i've put question on > this forum. > The overhead varies from generally 360 to 395 cycles .Sometimes it > also reduces close to 270 cycles. > Cycles consumed by the targetd code varies from 20 to 100 > cycles.Theoratically i thing cycles consumed should be less than > 20.Then why so many cycles ? and the output vary from 20 to 100 > cycles .Sometimes it crosses 100 cycles as well. Sure, but this is not unexpected. Think about pipelines and caches. > Sometimes the cycles consumed by targetted code become far less that > the RDTSC instrucion overhead. > > Is there better way to write above code. I'm sure there is. Jumping out of an inline asm isn't allowed at all in gcc, for example. We can't tell from your posting what you're trying to do. However, measuring time intervals on the order of 10 nanoseconds is going to be hard, whatever you do. Tell us what code you're actually trying to measure, and we might get somewhere. Andrew.
