Messages in this thread | | | Date | Tue, 29 Nov 2005 17:55:00 +1100 | From | Nick Piggin <> | Subject | Re: [RFC][PATCH] Runtime switching of the idle function [take 2] |
| |
Ingo Molnar wrote: > * Andrew Morton <akpm@osdl.org> 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. >
Why not just slightly cleanup and extend (eg. to ACPI) the hlt_counter thingy that many architectures already have?
Nick
-- SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |