linux-kernel - [PATCH 02/14] cpufreq: intel_pstate: Drop pointless initialization of PID parameters

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 12 Mar 2017 18:13:57 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: [PATCH 02/14] cpufreq: intel_pstate: Drop pointless initialization of PID parameters

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

The P-state selection algorithm used by intel_pstate for Atom
processors is not based on the PID controller and the initialization
of PID parametrs for those processors is pointless and confusing, so
drop it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/intel_pstate.c |   28 ++--------------------------
 1 file changed, 2 insertions(+), 26 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -1592,14 +1592,6 @@ static struct cpu_defaults core_params =
 };
 
 static const struct cpu_defaults silvermont_params = {
-	.pid_policy = {
-		.sample_rate_ms = 10,
-		.deadband = 0,
-		.setpoint = 60,
-		.p_gain_pct = 14,
-		.d_gain_pct = 0,
-		.i_gain_pct = 4,
-	},
 	.funcs = {
 		.get_max = atom_get_max_pstate,
 		.get_max_physical = atom_get_max_pstate,
@@ -1613,14 +1605,6 @@ static const struct cpu_defaults silverm
 };
 
 static const struct cpu_defaults airmont_params = {
-	.pid_policy = {
-		.sample_rate_ms = 10,
-		.deadband = 0,
-		.setpoint = 60,
-		.p_gain_pct = 14,
-		.d_gain_pct = 0,
-		.i_gain_pct = 4,
-	},
 	.funcs = {
 		.get_max = atom_get_max_pstate,
 		.get_max_physical = atom_get_max_pstate,
@@ -1654,14 +1638,6 @@ static const struct cpu_defaults knl_par
 };
 
 static const struct cpu_defaults bxt_params = {
-	.pid_policy = {
-		.sample_rate_ms = 10,
-		.deadband = 0,
-		.setpoint = 60,
-		.p_gain_pct = 14,
-		.d_gain_pct = 0,
-		.i_gain_pct = 4,
-	},
 	.funcs = {
 		.get_max = core_get_max_pstate,
 		.get_max_physical = core_get_max_pstate_physical,
@@ -2721,9 +2697,9 @@ static int __init intel_pstate_init(void
 		return -ENODEV;
 
 	cpu_def = (struct cpu_defaults *)id->driver_data;
-
-	copy_pid_params(&cpu_def->pid_policy);
 	copy_cpu_funcs(&cpu_def->funcs);
+	if (pstate_funcs.get_target_pstate == get_target_pstate_use_performance)
+		copy_pid_params(&cpu_def->pid_policy);
 
 	if (intel_pstate_msrs_not_valid())
 		return -ENODEV;