From: Ingo M. <mi...@el...> - 2005-11-29 06:44:34
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* Andrew Morton <ak...@os...> wrote: > > The way to solve this was to set > > idle=poll. The original patch I sent was to allow the user to change to > > idle=poll dynamically. This way they could switch to the poll_idle and > > run there tests (requiring tsc not to drift) and then switch back to the > > default idle to save on electricity. > > Use gettimeofday()? > > If it's just for some sort of instrumentation, run NR_CPUS instances > of a niced-down busyloop, pin each one to a different CPU? That way > the idle function doesn't get called at all.. idle=poll is also frequently done for performance reasons [it reduces idle wakeup latency by 10 usecs] - while it could be turned off if the system has been idle for some time. E.g. cpufreqd could sample idle time and turn on/off idle=poll. High-performance setups could enable it all the time. as long as it can be done with zero-cost, i dont see why Steven's patch wouldnt be a plus for us. It's a performance thing, and having runtime switches for seemless performance features cannot be bad. Ingo |