linux-kernel - [RFC PATCH 6/8] cpufreq: intel

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]

Message-Id: <20240905092645.2885200-7-christian.loehle@arm.com>
Date: Thu,  5 Sep 2024 10:26:43 +0100
From: Christian Loehle <christian.loehle@....com>
To: linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	rafael@...nel.org,
	peterz@...radead.org
Cc: juri.lelli@...hat.com,
	mingo@...hat.com,
	dietmar.eggemann@....com,
	vschneid@...hat.com,
	vincent.guittot@...aro.org,
	Johannes.Thumshirn@....com,
	adrian.hunter@...el.com,
	ulf.hansson@...aro.org,
	bvanassche@....org,
	andres@...razel.de,
	asml.silence@...il.com,
	linux-block@...r.kernel.org,
	io-uring@...r.kernel.org,
	qyousef@...alina.io,
	dsmythies@...us.net,
	axboe@...nel.dk,
	Christian Loehle <christian.loehle@....com>
Subject: [RFC PATCH 6/8] cpufreq: intel_pstate: Remove iowait boost

Analogous to schedutil, remove iowait boost for the same reasons.

Signed-off-by: Christian Loehle <christian.loehle@....com>
---
 drivers/cpufreq/intel_pstate.c | 50 ++--------------------------------
 1 file changed, 3 insertions(+), 47 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index c0278d023cfc..7f30b2569bb3 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -191,7 +191,6 @@ struct global_params {
  * @policy:		CPUFreq policy value
  * @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
@@ -245,7 +244,6 @@ struct cpudata {
 	struct acpi_processor_performance acpi_perf_data;
 	bool valid_pss_table;
 #endif
-	unsigned int iowait_boost;
 	s16 epp_powersave;
 	s16 epp_policy;
 	s16 epp_default;
@@ -2136,28 +2134,7 @@ static inline void intel_pstate_update_util_hwp_local(struct cpudata *cpu,
 {
 	cpu->sample.time = time;
 
-	if (cpu->sched_flags & SCHED_CPUFREQ_IOWAIT) {
-		bool do_io = false;
-
-		cpu->sched_flags = 0;
-		/*
-		 * Set iowait_boost flag and update time. Since IO WAIT flag
-		 * is set all the time, we can't just conclude that there is
-		 * some IO bound activity is scheduled on this CPU with just
-		 * one occurrence. If we receive at least two in two
-		 * consecutive ticks, then we treat as boost candidate.
-		 */
-		if (time_before64(time, cpu->last_io_update + 2 * TICK_NSEC))
-			do_io = true;
-
-		cpu->last_io_update = time;
-
-		if (do_io)
-			intel_pstate_hwp_boost_up(cpu);
-
-	} else {
-		intel_pstate_hwp_boost_down(cpu);
-	}
+	intel_pstate_hwp_boost_down(cpu);
 }
 
 static inline void intel_pstate_update_util_hwp(struct update_util_data *data,
@@ -2240,9 +2217,6 @@ static inline int32_t get_target_pstate(struct cpudata *cpu)
 	busy_frac = div_fp(sample->mperf << cpu->aperf_mperf_shift,
 			   sample->tsc);
 
-	if (busy_frac < cpu->iowait_boost)
-		busy_frac = cpu->iowait_boost;
-
 	sample->busy_scaled = busy_frac * 100;
 
 	target = READ_ONCE(global.no_turbo) ?
@@ -2303,7 +2277,7 @@ static void intel_pstate_adjust_pstate(struct cpudata *cpu)
 		sample->aperf,
 		sample->tsc,
 		get_avg_frequency(cpu),
-		fp_toint(cpu->iowait_boost * 100));
+		0);
 }
 
 static void intel_pstate_update_util(struct update_util_data *data, u64 time,
@@ -2317,24 +2291,6 @@ static void intel_pstate_update_util(struct update_util_data *data, u64 time,
 		return;
 
 	delta_ns = time - cpu->last_update;
-	if (flags & SCHED_CPUFREQ_IOWAIT) {
-		/* Start over if the CPU may have been idle. */
-		if (delta_ns > TICK_NSEC) {
-			cpu->iowait_boost = ONE_EIGHTH_FP;
-		} else if (cpu->iowait_boost >= ONE_EIGHTH_FP) {
-			cpu->iowait_boost <<= 1;
-			if (cpu->iowait_boost > int_tofp(1))
-				cpu->iowait_boost = int_tofp(1);
-		} else {
-			cpu->iowait_boost = ONE_EIGHTH_FP;
-		}
-	} else if (cpu->iowait_boost) {
-		/* Clear iowait_boost if the CPU may have been idle. */
-		if (delta_ns > TICK_NSEC)
-			cpu->iowait_boost = 0;
-		else
-			cpu->iowait_boost >>= 1;
-	}
 	cpu->last_update = time;
 	delta_ns = time - cpu->sample.time;
 	if ((s64)delta_ns < INTEL_PSTATE_SAMPLING_INTERVAL)
@@ -2832,7 +2788,7 @@ static void intel_cpufreq_trace(struct cpudata *cpu, unsigned int trace_type, in
 		sample->aperf,
 		sample->tsc,
 		get_avg_frequency(cpu),
-		fp_toint(cpu->iowait_boost * 100));
+		0);
 }
 
 static void intel_cpufreq_hwp_update(struct cpudata *cpu, u32 min, u32 max,
-- 
2.34.1