Ingo Molnar wrote:
* Andrew Morton <[email protected]> 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.
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