| 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
| ||
|
Date: Wed, 14 Sep 2016 01:59:01 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM list <linux-pm@...r.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Peter Zijlstra <peterz@...radead.org>,
Viresh Kumar <viresh.kumar@...aro.org>,
Ingo Molnar <mingo@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Morten Rasmussen <morten.rasmussen@....com>,
Juri Lelli <Juri.Lelli@....com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steve Muckle <smuckle@...aro.org>,
Doug Smythies <doug.smythies@...il.com>
Subject: [Update][PATCH 3/3] cpufreq: intel_pstate: Use IOWAIT flag in Atom algorithm
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Modify the P-state selection algorithm for Atom processors to use
the new SCHED_CPUFREQ_IOWAIT flag instead of the questionable
get_cpu_iowait_time_us() function.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
The PID uses percents not fractions, so pass sample->busy_scaled instead of
busy_frac to it in get_target_pstate_use_cpu_load().
---
drivers/cpufreq/intel_pstate.c | 58 +++++++++++++++++++++--------------------
1 file changed, 31 insertions(+), 27 deletions(-)
Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -181,6 +181,8 @@ struct _pid {
* @cpu: CPU number for this instance data
* @update_util: CPUFreq utility callback information
* @update_util_set: CPUFreq utility callback is set
+ * @iowait_boost: iowait-related boost fraction
+ * @last_update: Time of the last update.
* @pstate: Stores P state limits for this CPU
* @vid: Stores VID limits for this CPU
* @pid: Stores PID parameters for this CPU
@@ -206,6 +208,7 @@ struct cpudata {
struct vid_data vid;
struct _pid pid;
+ u64 last_update;
u64 last_sample_time;
u64 prev_aperf;
u64 prev_mperf;
@@ -216,6 +219,7 @@ struct cpudata {
struct acpi_processor_performance acpi_perf_data;
bool valid_pss_table;
#endif
+ unsigned int iowait_boost;
};
static struct cpudata **all_cpu_data;
@@ -229,6 +233,7 @@ static struct cpudata **all_cpu_data;
* @p_gain_pct: PID proportional gain
* @i_gain_pct: PID integral gain
* @d_gain_pct: PID derivative gain
+ * @boost_iowait: Whether or not to use iowait boosting.
*
* Stores per CPU model static PID configuration data.
*/
@@ -240,6 +245,7 @@ struct pstate_adjust_policy {
int p_gain_pct;
int d_gain_pct;
int i_gain_pct;
+ bool boost_iowait;
};
/**
@@ -1037,6 +1043,7 @@ static struct cpu_defaults silvermont_pa
.p_gain_pct = 14,
.d_gain_pct = 0,
.i_gain_pct = 4,
+ .boost_iowait = true,
},
.funcs = {
.get_max = atom_get_max_pstate,
@@ -1058,6 +1065,7 @@ static struct cpu_defaults airmont_param
.p_gain_pct = 14,
.d_gain_pct = 0,
.i_gain_pct = 4,
+ .boost_iowait = true,
},
.funcs = {
.get_max = atom_get_max_pstate,
@@ -1099,6 +1107,7 @@ static struct cpu_defaults bxt_params =
.p_gain_pct = 14,
.d_gain_pct = 0,
.i_gain_pct = 4,
+ .boost_iowait = true,
},
.funcs = {
.get_max = core_get_max_pstate,
@@ -1222,36 +1231,18 @@ static inline int32_t get_avg_pstate(str
static inline int32_t get_target_pstate_use_cpu_load(struct cpudata *cpu)
{
struct sample *sample = &cpu->sample;
- u64 cummulative_iowait, delta_iowait_us;
- u64 delta_iowait_mperf;
- u64 mperf, now;
- int32_t cpu_load;
+ int32_t busy_frac, boost;
- cummulative_iowait = get_cpu_iowait_time_us(cpu->cpu, &now);
+ busy_frac = div_fp(sample->mperf, sample->tsc);
- /*
- * Convert iowait time into number of IO cycles spent at max_freq.
- * IO is considered as busy only for the cpu_load algorithm. For
- * performance this is not needed since we always try to reach the
- * maximum P-State, so we are already boosting the IOs.
- */
- delta_iowait_us = cummulative_iowait - cpu->prev_cummulative_iowait;
- delta_iowait_mperf = div64_u64(delta_iowait_us * cpu->pstate.scaling *
- cpu->pstate.max_pstate, MSEC_PER_SEC);
+ boost = cpu->iowait_boost;
+ cpu->iowait_boost >>= 1;
- mperf = cpu->sample.mperf + delta_iowait_mperf;
- cpu->prev_cummulative_iowait = cummulative_iowait;
-
- /*
- * The load can be estimated as the ratio of the mperf counter
- * running at a constant frequency during active periods
- * (C0) and the time stamp counter running at the same frequency
- * also during C-states.
- */
- cpu_load = div64_u64(int_tofp(100) * mperf, sample->tsc);
- cpu->sample.busy_scaled = cpu_load;
+ if (busy_frac < boost)
+ busy_frac = boost;
- return get_avg_pstate(cpu) - pid_calc(&cpu->pid, cpu_load);
+ sample->busy_scaled = busy_frac * 100;
+ return get_avg_pstate(cpu) - pid_calc(&cpu->pid, sample->busy_scaled);
}
static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
@@ -1332,8 +1323,21 @@ static void intel_pstate_update_util(str
unsigned int flags)
{
struct cpudata *cpu = container_of(data, struct cpudata, update_util);
- u64 delta_ns = time - cpu->sample.time;
+ u64 delta_ns;
+
+ if (pid_params.boost_iowait) {
+ if (flags & SCHED_CPUFREQ_IOWAIT) {
+ cpu->iowait_boost = int_tofp(1);
+ } else if (cpu->iowait_boost) {
+ /* Clear iowait_boost if the CPU may have been idle. */
+ delta_ns = time - cpu->last_update;
+ if (delta_ns > TICK_NSEC)
+ cpu->iowait_boost = 0;
+ }
+ cpu->last_update = time;
+ }
+ delta_ns = time - cpu->sample.time;
if ((s64)delta_ns >= pid_params.sample_rate_ns) {
bool sample_taken = intel_pstate_sample(cpu, time);
Powered by blists - more mailing lists