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Date: Fri, 12 Oct 2018 10:28:26 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Daniel Lezcano <daniel.lezcano@...aro.org> Cc: rafael@...nel.org, rjw@...ysocki.net, linux-pm@...r.kernel.org, Todd Kjos <tkjos@...gle.com>, Joel Fernandes <joelaf@...gle.com>, Colin Cross <ccross@...roid.com>, Ramesh Thomas <ramesh.thomas@...el.com>, Mel Gorman <mgorman@...e.de>, Ingo Molnar <mingo@...hat.com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, Alex Shi <alex.shi@...aro.org>, Thomas Gleixner <tglx@...utronix.de>, Philippe Ombredanne <pombredanne@...b.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Kate Stewart <kstewart@...uxfoundation.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH V2 2/2] cpuidle/drivers/menu: Remove get_loadavg in the performance multiplier On Thu, Oct 04, 2018 at 02:04:03PM +0200, Daniel Lezcano wrote: > The function get_loadavg() returns almost always zero. To be more > precise, statistically speaking for a total of 1023379 times passing > in the function, the load is equal to zero 1020728 times, greater than > 100, 610 times, the remaining is between 0 and 5. > > In 2011, the get_loadavg() was removed from the Android tree because > of the above [1]. At this time, the load was: > > unsigned long this_cpu_load(void) > { > struct rq *this = this_rq(); > return this->cpu_load[0]; > } > > In 2014, the code was changed by commit 372ba8cb46b2 (cpuidle: menu: Lookup CPU > runqueues less) and the load is: > > void get_iowait_load(unsigned long *nr_waiters, unsigned long *load) > { > struct rq *rq = this_rq(); > *nr_waiters = atomic_read(&rq->nr_iowait); > *load = rq->load.weight; > } > > with the same result. > > Both measurements show using the load in this code path does no matter > anymore. Removing it. > > [1] https://android.googlesource.com/kernel/common/+/4dedd9f124703207895777ac6e91dacde0f7cc17 > > Cc: Peter Zijlstra <peterz@...radead.org> > Cc: Todd Kjos <tkjos@...gle.com> > Cc: Joel Fernandes <joelaf@...gle.com> > Cc: Colin Cross <ccross@...roid.com> > Cc: Ramesh Thomas <ramesh.thomas@...el.com> > Cc: Mel Gorman <mgorman@...e.de> > Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
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