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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-09-02 13:49:18 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-15 16:51:27 +0200
commit47fe38fcff0517e67d395c039d2e26d2de688a60 (patch)
treeada38f4e1aa644354b9de4c2cb128719e9e64a9e /arch/x86/kernel
parent5cbc19a983141729d716be17197028434127b376 (diff)
x86: sched: Provide arch implementations using aperf/mperf
APERF/MPERF support for cpu_power. APERF/MPERF is arch defined to be a relative scale of work capacity per logical cpu, this is assumed to include SMT and Turbo mode. APERF/MPERF are specified to both reset to 0 when either counter wraps, which is highly inconvenient, since that'll give a blimp when that happens. The manual specifies writing 0 to the counters after each read, but that's 1) too expensive, and 2) destroys the possibility of sharing these counters with other users, so we live with the blimp - the other existing user does too. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/Makefile2
-rw-r--r--arch/x86/kernel/cpu/sched.c55
2 files changed, 56 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index c1f253dac15..8dd30638fe4 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -13,7 +13,7 @@ CFLAGS_common.o := $(nostackp)
obj-y := intel_cacheinfo.o addon_cpuid_features.o
obj-y += proc.o capflags.o powerflags.o common.o
-obj-y += vmware.o hypervisor.o
+obj-y += vmware.o hypervisor.o sched.o
obj-$(CONFIG_X86_32) += bugs.o cmpxchg.o
obj-$(CONFIG_X86_64) += bugs_64.o
diff --git a/arch/x86/kernel/cpu/sched.c b/arch/x86/kernel/cpu/sched.c
new file mode 100644
index 00000000000..6c00a8f3cce
--- /dev/null
+++ b/arch/x86/kernel/cpu/sched.c
@@ -0,0 +1,55 @@
+#include <linux/sched.h>
+#include <linux/math64.h>
+#include <linux/percpu.h>
+#include <linux/irqflags.h>
+
+#include <asm/cpufeature.h>
+#include <asm/processor.h>
+
+#ifdef CONFIG_SMP
+
+static DEFINE_PER_CPU(struct aperfmperf, old_perf);
+
+static unsigned long scale_aperfmperf(void)
+{
+ struct aperfmperf val, *old = &__get_cpu_var(old_perf);
+ unsigned long ratio, flags;
+
+ local_irq_save(flags);
+ get_aperfmperf(&val);
+ local_irq_restore(flags);
+
+ ratio = calc_aperfmperf_ratio(old, &val);
+ *old = val;
+
+ return ratio;
+}
+
+unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+ /*
+ * do aperf/mperf on the cpu level because it includes things
+ * like turbo mode, which are relevant to full cores.
+ */
+ if (boot_cpu_has(X86_FEATURE_APERFMPERF))
+ return scale_aperfmperf();
+
+ /*
+ * maybe have something cpufreq here
+ */
+
+ return default_scale_freq_power(sd, cpu);
+}
+
+unsigned long arch_scale_smt_power(struct sched_domain *sd, int cpu)
+{
+ /*
+ * aperf/mperf already includes the smt gain
+ */
+ if (boot_cpu_has(X86_FEATURE_APERFMPERF))
+ return SCHED_LOAD_SCALE;
+
+ return default_scale_smt_power(sd, cpu);
+}
+
+#endif