From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Linux PM list <linux-pm@vger.kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: [PATCH] cpufreq: intel_pstate: Always set max P-state in performance mode
Date: Mon, 24 Oct 2016 15:20:39 +0200 [thread overview]
Message-ID: <1490845.P5jEmYeGuo@vostro.rjw.lan> (raw)
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The only times when intel_pstate checks the policy set for a given
CPU is the initialization of that CPU and updates of its settings
from cpufreq leading to intel_pstate_set_policy() invocatios.
That is insufficient, however, because intel_pstate uses the same
P-state selection function for all CPUs regardless of the policy
setting for each of them and the P-state limits are shared between
them. Thus if the policy is set to "performance" for a particular
CPU, it may not behave as expected if the cpufreq settings are
changed subsequently for another CPU.
That can be easily demonstrated by writing "performance" to
scaling_governor for all CPUs and then switching it to "powersave"
for one of them in which case all of the CPUs will behave as though
their scaling_governor were "powersave" (even though the policy
still appears to be "performance" for the remaining CPUs).
Fix this problem by modifying intel_pstate_adjust_busy_pstate() to
always set the P-state to the maximum allowed by the current limits
if the policy is set to "performance" for the given CPU.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/cpufreq/intel_pstate.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -179,6 +179,7 @@ struct _pid {
/**
* struct cpudata - Per CPU instance data storage
* @cpu: CPU number for this instance data
+ * @policy: CPUFreq policy value
* @update_util: CPUFreq utility callback information
* @update_util_set: CPUFreq utility callback is set
* @iowait_boost: iowait-related boost fraction
@@ -201,6 +202,7 @@ struct _pid {
struct cpudata {
int cpu;
+ unsigned int policy;
struct update_util_data update_util;
bool update_util_set;
@@ -1331,7 +1333,8 @@ static inline void intel_pstate_adjust_b
from = cpu->pstate.current_pstate;
- target_pstate = pstate_funcs.get_target_pstate(cpu);
+ target_pstate = cpu->policy == CPUFREQ_POLICY_PERFORMANCE ?
+ cpu->pstate.turbo_pstate : pstate_funcs.get_target_pstate(cpu);
intel_pstate_update_pstate(cpu, target_pstate);
@@ -1498,6 +1501,8 @@ static int intel_pstate_set_policy(struc
policy->cpuinfo.max_freq, policy->max);
cpu = all_cpu_data[policy->cpu];
+ cpu->policy = policy->policy;
+
if (cpu->pstate.max_pstate_physical > cpu->pstate.max_pstate &&
policy->max < policy->cpuinfo.max_freq &&
policy->max > cpu->pstate.max_pstate * cpu->pstate.scaling) {
@@ -1505,7 +1510,7 @@ static int intel_pstate_set_policy(struc
policy->max = policy->cpuinfo.max_freq;
}
- if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
+ if (cpu->policy == CPUFREQ_POLICY_PERFORMANCE) {
limits = &performance_limits;
if (policy->max >= policy->cpuinfo.max_freq) {
pr_debug("set performance\n");
@@ -1541,7 +1546,7 @@ static int intel_pstate_set_policy(struc
limits->max_perf = round_up(limits->max_perf, FRAC_BITS);
out:
- if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
+ if (cpu->policy == CPUFREQ_POLICY_PERFORMANCE) {
/*
* NOHZ_FULL CPUs need this as the governor callback may not
* be invoked on them.
next reply other threads:[~2016-10-24 13:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-24 13:20 Rafael J. Wysocki [this message]
2016-10-24 21:13 ` [PATCH v2] cpufreq: intel_pstate: Always set max P-state in performance mode Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1490845.P5jEmYeGuo@vostro.rjw.lan \
--to=rjw@rjwysocki.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=srinivas.pandruvada@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).