* [PATCH 2.5.54] cpufreq: update timer notifiers
@ 2003-01-02 21:45 Dominik Brodowski
0 siblings, 0 replies; only message in thread
From: Dominik Brodowski @ 2003-01-02 21:45 UTC (permalink / raw)
To: torvalds; +Cc: linux-kernel, cpufreq
- The global loops_per_jiffy can only be safely adjusted on UP.
- x86 per-CPU loops_per_jiffy is not dependend of TSC, so move it to
non-TSC code.
- Save reference values so that rounding errors do not accumulate
diff -ruN linux-original/arch/i386/kernel/cpu/common.c linux/arch/i386/kernel/cpu/common.c
--- linux-original/arch/i386/kernel/cpu/common.c 2003-01-02 22:03:50.000000000 +0100
+++ linux/arch/i386/kernel/cpu/common.c 2003-01-02 21:03:31.000000000 +0100
@@ -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);
diff -ruN linux-original/arch/i386/kernel/timers/timer_tsc.c linux/arch/i386/kernel/timers/timer_tsc.c
--- linux-original/arch/i386/kernel/timers/timer_tsc.c 2003-01-02 22:03:50.000000000 +0100
+++ linux/arch/i386/kernel/timers/timer_tsc.c 2003-01-02 22:03:34.000000000 +0100
@@ -188,47 +188,47 @@
}
-#ifdef CONFIG_CPU_FREQ
+#if defined(CONFIG_CPU_FREQ) && !defined(CONFIG_SMP)
+
+static unsigned long fast_gettimeoffset_ref = 0;
+static unsigned long cpu_khz_ref = 0;
+static unsigned int ref_freq = 0;
static int
-time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
+tsc_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
struct cpufreq_freqs *freq = data;
- unsigned int i;
- if (!cpu_has_tsc)
+ if (!use_tsc)
return 0;
+ if (!fast_gettimeoffset_ref) {
+ fast_gettimeoffset_ref = fast_gettimeoffset_quotient;
+ cpu_khz_ref = cpu_khz;
+ ref_freq = freq->old;
+ }
+
switch (val) {
case CPUFREQ_PRECHANGE:
- if ((freq->old < freq->new) &&
- ((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == 0))) {
- cpu_khz = cpufreq_scale(cpu_khz, freq->old, freq->new);
- fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_quotient, freq->new, freq->old);
+ if (freq->old < freq->new) {
+ fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_ref, freq->new, ref_freq);
+ cpu_khz = cpufreq_scale(cpu_khz_ref, ref_freq, freq->new);
}
- for (i=0; i<NR_CPUS; i++)
- if ((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == i))
- cpu_data[i].loops_per_jiffy = cpufreq_scale(cpu_data[i].loops_per_jiffy, freq->old, freq->new);
break;
-
case CPUFREQ_POSTCHANGE:
- if ((freq->new < freq->old) &&
- ((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == 0))) {
- cpu_khz = cpufreq_scale(cpu_khz, freq->old, freq->new);
- fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_quotient, freq->new, freq->old);
+ if (freq->new < freq->old) {
+ fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_ref, freq->new, ref_freq);
+ cpu_khz = cpufreq_scale(cpu_khz_ref, ref_freq, freq->new);
}
- for (i=0; i<NR_CPUS; i++)
- if ((freq->cpu == CPUFREQ_ALL_CPUS) || (freq->cpu == i))
- cpu_data[i].loops_per_jiffy = cpufreq_scale(cpu_data[i].loops_per_jiffy, freq->old, freq->new);
break;
}
return 0;
}
-static struct notifier_block time_cpufreq_notifier_block = {
- .notifier_call = time_cpufreq_notifier
+static struct notifier_block tsc_cpufreq_notifier_block = {
+ .notifier_call = tsc_cpufreq_notifier
};
#endif
@@ -282,8 +282,8 @@
"0" (eax), "1" (edx));
printk("Detected %lu.%03lu MHz processor.\n", cpu_khz / 1000, cpu_khz % 1000);
}
-#ifdef CONFIG_CPU_FREQ
- cpufreq_register_notifier(&time_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
+#if defined(CONFIG_CPU_FREQ) && !defined(CONFIG_SMP)
+ cpufreq_register_notifier(&tsc_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
#endif
return 0;
}
diff -ruN linux-original/kernel/cpufreq.c linux/kernel/cpufreq.c
--- linux-original/kernel/cpufreq.c 2003-01-02 22:03:50.000000000 +0100
+++ linux/kernel/cpufreq.c 2003-01-02 21:03:31.000000000 +0100
@@ -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
/**
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