linux-kernel - [RFCv3 PATCH 14/48] arm: Frequency invariant scheduler load-tracking support

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: <1423074685-6336-15-git-send-email-morten.rasmussen@arm.com>
Date:	Wed,  4 Feb 2015 18:30:51 +0000
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	peterz@...radead.org, mingo@...hat.com
Cc:	vincent.guittot@...aro.org, dietmar.eggemann@....com,
	yuyang.du@...el.com, preeti@...ux.vnet.ibm.com,
	mturquette@...aro.org, nico@...aro.org, rjw@...ysocki.net,
	juri.lelli@....com, linux-kernel@...r.kernel.org,
	Morten Rasmussen <Morten.Rasmussen@....com>,
	Russell King <linux@....linux.org.uk>
Subject: [RFCv3 PATCH 14/48] arm: Frequency invariant scheduler load-tracking support

From: Morten Rasmussen <Morten.Rasmussen@....com>

Implements arch-specific function to provide the scheduler with a
frequency scaling correction factor for more accurate load-tracking. The
factor is:

	current_freq(cpu) * SCHED_CAPACITY_SCALE / max_freq(cpu)

This implementation only provides frequency invariance. No
micro-architecture invariance yet.

Cc: Russell King <linux@....linux.org.uk>
Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
---
 arch/arm/kernel/topology.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index 08b7847..a1274e6 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -169,6 +169,39 @@ static void update_cpu_capacity(unsigned int cpu)
 		cpu, arch_scale_cpu_capacity(NULL, cpu));
 }
 
+/*
+ * Scheduler load-tracking scale-invariance
+ *
+ * Provides the scheduler with a scale-invariance correction factor that
+ * compensates for frequency scaling.
+ */
+
+static DEFINE_PER_CPU(atomic_long_t, cpu_curr_freq);
+static DEFINE_PER_CPU(atomic_long_t, cpu_max_freq);
+
+/* cpufreq callback function setting current cpu frequency */
+void arch_scale_set_curr_freq(int cpu, unsigned long freq)
+{
+	atomic_long_set(&per_cpu(cpu_curr_freq, cpu), freq);
+}
+
+/* cpufreq callback function setting max cpu frequency */
+void arch_scale_set_max_freq(int cpu, unsigned long freq)
+{
+	atomic_long_set(&per_cpu(cpu_max_freq, cpu), freq);
+}
+
+unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu)
+{
+	unsigned long curr = atomic_long_read(&per_cpu(cpu_curr_freq, cpu));
+	unsigned long max = atomic_long_read(&per_cpu(cpu_max_freq, cpu));
+
+	if (!curr || !max)
+		return SCHED_CAPACITY_SCALE;
+
+	return (curr * SCHED_CAPACITY_SCALE) / max;
+}
+
 #else
 static inline void parse_dt_topology(void) {}
 static inline void update_cpu_capacity(unsigned int cpuid) {}
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/