linux-kernel - Re: [RFC 8/9] intel_pstate: ignore scheduler cpufreq callbacks on remote CPUs

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Message-ID: <11658751.uecjsoxtRb@aspire.rjw.lan>
Date:   Thu, 30 Mar 2017 00:15:33 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>, linaro-kernel@...ts.linaro.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        smuckle.linux@...il.com, juri.lelli@....com,
        Morten.Rasmussen@....com, patrick.bellasi@....com,
        eas-dev@...ts.linaro.org
Subject: Re: [RFC 8/9] intel_pstate: ignore scheduler cpufreq callbacks on remote CPUs

On Thursday, March 09, 2017 05:15:18 PM Viresh Kumar wrote:
> From: Steve Muckle <smuckle.linux@...il.com>
> 
> In preparation for the scheduler cpufreq callback happening on remote
> CPUs, check for this case in intel_pstate which currently requires the
> callback run on the local CPU. Such callbacks are ignored for now.
> 
> Signed-off-by: Steve Muckle <smuckle.linux@...il.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  drivers/cpufreq/intel_pstate.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 3d37219a0dd7..bd60f1cd7ea6 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -1930,6 +1930,9 @@ static void intel_pstate_update_util(struct update_util_data *data, u64 time,
>  	struct cpudata *cpu = container_of(data, struct cpudata, update_util);
>  	u64 delta_ns;
>  
> +	if (smp_processor_id() != data->cpu)
> +		return;
> +
>  	if (pstate_funcs.get_target_pstate == get_target_pstate_use_cpu_load) {
>  		if (flags & SCHED_CPUFREQ_IOWAIT) {
>  			cpu->iowait_boost = int_tofp(1);
> 

This would need to be updated on top of some intel_pstate changes in the queue.

Thanks,
Rafael