Re: [PATCH] cpufreq: intel_pstate: Drop boost_iowait flag

[Srinivas Pandruvada]

On Wed, 2016-10-19 at 02:53 +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> 
> The "IOwait boosting" mechanism is only used by the
> get_target_pstate_use_cpu_load() governor function and the
> boost_iowait flag in pid_params is always set when that function
> is in use (and it is never set otherwise).ÂÂThis means that the
> boost_iowait flag is in fact redundant and may be dropped.
> 
> For this reason, replace the boost_iowait flag check in
> intel_pstate_update_util() with an equivalent check against
> pstate_funcs.get_target_pstate and drop that flag.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>

> ---
> Âdrivers/cpufreq/intel_pstate.c |ÂÂÂÂ7 +------
> Â1 file changed, 1 insertion(+), 6 deletions(-)
> 
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -233,7 +233,6 @@ static struct cpudata **all_cpu_data;
> Â * @p_gain_pct:		PID proportional gain
> Â * @i_gain_pct:		PID integral gain
> Â * @d_gain_pct:		PID derivative gain
> - * @boost_iowait:	Whether or not to use iowait boosting.
> Â *
> Â * Stores per CPU model static PID configuration data.
> Â */
> @@ -245,7 +244,6 @@ struct pstate_adjust_policy {
> Â	int p_gain_pct;
> Â	int d_gain_pct;
> Â	int i_gain_pct;
> -	bool boost_iowait;
> Â};
> Â
> Â/**
> @@ -1043,7 +1041,6 @@ static const struct cpu_defaults silverm
> Â		.p_gain_pct = 14,
> Â		.d_gain_pct = 0,
> Â		.i_gain_pct = 4,
> -		.boost_iowait = true,
> Â	},
> Â	.funcs = {
> Â		.get_max = atom_get_max_pstate,
> @@ -1065,7 +1062,6 @@ static const struct cpu_defaults airmont
> Â		.p_gain_pct = 14,
> Â		.d_gain_pct = 0,
> Â		.i_gain_pct = 4,
> -		.boost_iowait = true,
> Â	},
> Â	.funcs = {
> Â		.get_max = atom_get_max_pstate,
> @@ -1107,7 +1103,6 @@ static const struct cpu_defaults bxt_par
> Â		.p_gain_pct = 14,
> Â		.d_gain_pct = 0,
> Â		.i_gain_pct = 4,
> -		.boost_iowait = true,
> Â	},
> Â	.funcs = {
> Â		.get_max = core_get_max_pstate,
> @@ -1346,7 +1341,7 @@ static void intel_pstate_update_util(str
> Â	struct cpudata *cpu = container_of(data, struct cpudata,
> update_util);
> Â	u64 delta_ns;
> Â
> -	if (pid_params.boost_iowait) {
> +	if (pstate_funcs.get_target_pstate ==
> get_target_pstate_use_cpu_load) {
> Â		if (flags & SCHED_CPUFREQ_IOWAIT) {
> Â			cpu->iowait_boost = int_tofp(1);
> Â		} else if (cpu->iowait_boost) {
> 
> --
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