cpufreq: update timer notifiers

diff -ruN linux-original/arch/i386/kernel/cpu/common.c linux/arch/i386/kernel/cpu/common.c
@@ -1,5 +1,7 @@
 #include <linux/init.h>
 #include <linux/string.h>
+#include <linux/cpufreq.h>
+#include <linux/notifier.h>
 #include <linux/delay.h>
 #include <linux/smp.h>
 #include <asm/semaphore.h>

@@ -45,6 +47,41 @@
 }
 __setup("cachesize=", cachesize_setup);
 
+#ifdef CONFIG_CPU_FREQ
+static unsigned long loops_per_jiffy_ref = 0;
+static unsigned int  ref_freq = 0;
+
+static int
+loops_per_jiffy_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
+				       void *data)
+{
+	struct cpufreq_freqs *freq = data;
+
+	if (!loops_per_jiffy_ref) {
+		loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
+		ref_freq = freq->old;
+	}
+
+	switch (val) {
+	case CPUFREQ_PRECHANGE:
+		if (freq->old < freq->new)
+		        cpu_data[freq->cpu].loops_per_jiffy = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
+		break;
+	case CPUFREQ_POSTCHANGE:
+		if (freq->new < freq->old)
+		        cpu_data[freq->cpu].loops_per_jiffy = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
+		break;
+	}
+
+	return 0;
+}
+
+static struct notifier_block loops_per_jiffy_cpufreq_notifier_block = {
+	.notifier_call	= loops_per_jiffy_cpufreq_notifier
+};
+#endif
+
+
 int __init get_model_name(struct cpuinfo_x86 *c)
 {
 	unsigned int *v;

@@ -354,6 +391,16 @@
 			boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
 	}
 
+	/*
+	 * Update the per-CPU loops_per_jiffy count on CPU frequency
+	 * transitions
+	 */
+#ifdef CONFIG_CPU_FREQ
+	if (c == &boot_cpu_data) {
+			cpufreq_register_notifier(&loops_per_jiffy_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
+	}
+#endif
+
 	/* Init Machine Check Exception if available. */
 #ifdef CONFIG_X86_MCE
 	mcheck_init(c);

78 lines not on this page · raw message

diff -ruN linux-original/kernel/cpufreq.c linux/kernel/cpufreq.c
@@ -927,17 +927,27 @@
  * adjust_jiffies - adjust the system "loops_per_jiffy"
  *
  * This function alters the system "loops_per_jiffy" for the clock
- * speed change. Note that loops_per_jiffy is only updated if all
- * CPUs are affected - else there is a need for per-CPU loops_per_jiffy
- * values which are provided by various architectures. 
+ * speed change. Note that loops_per_jiffy cannot be updated on SMP
+ * systems as each CPU might be scaled differently. So, use the arch 
+ * per-CPU loops_per_jiffy value wherever possible.
  */
+#ifndef CONFIG_SMP
+static unsigned long l_p_j_ref = 0;
+static unsigned int  l_p_j_ref_freq = 0;
+
 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 {
+	if (!l_p_j_ref_freq) {
+		l_p_j_ref = loops_per_jiffy;
+		l_p_j_ref_freq = ci->old;
+	}
 	if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
 	    (val == CPUFREQ_POSTCHANGE && ci->old > ci->new))
-		if (ci->cpu == CPUFREQ_ALL_CPUS)
-			loops_per_jiffy = cpufreq_scale(loops_per_jiffy, ci->old, ci->new);
+		loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, ci->new);
 }
+#else
+#define adjust_jiffies(...)
+#endif
 
 
 /**