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GPL version 2 and no later version. This patch is provided as is, with no
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the use/inability to use this patch. Any use of the attached is considered
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From: Alok N Kataria <[email protected]>
Move the basic global variable definitions and sched_clock handling in the
common "tsc.c" file.
- Unify notsc kernel command line handling for 32 bit and 64bit.
- Functional changes for 64bit.
- "tsc_disabled" is updated if "notsc" is passed at boottime.
- Fallback to jiffies for sched_clock, incase notsc is passed on
commandline.
Signed-off-by: Alok N Kataria <[email protected]>
Signed-off-by: Dan Hecht <[email protected]>
---
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/time_32.c | 3 --
arch/x86/kernel/tsc.c | 86 +++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/tsc_32.c | 86 +--------------------------------------------
arch/x86/kernel/tsc_64.c | 67 ++++++-----------------------------
5 files changed, 100 insertions(+), 144 deletions(-)
create mode 100644 arch/x86/kernel/tsc.c
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index a33513d..631141b 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -34,7 +34,7 @@ obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o
obj-y += bootflag.o e820.o
obj-y += pci-dma.o quirks.o i8237.o topology.o kdebugfs.o
obj-y += alternative.o i8253.o pci-nommu.o
-obj-y += tsc_$(BITS).o io_delay.o rtc.o
+obj-y += tsc_$(BITS).o io_delay.o rtc.o tsc.o
obj-$(CONFIG_X86_TRAMPOLINE) += trampoline.o
obj-y += process.o
diff --git a/arch/x86/kernel/time_32.c b/arch/x86/kernel/time_32.c
index 5f29f12..059ca6e 100644
--- a/arch/x86/kernel/time_32.c
+++ b/arch/x86/kernel/time_32.c
@@ -39,9 +39,6 @@
#include "do_timer.h"
-unsigned int cpu_khz; /* Detected as we calibrate the TSC */
-EXPORT_SYMBOL(cpu_khz);
-
int timer_ack;
unsigned long profile_pc(struct pt_regs *regs)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
new file mode 100644
index 0000000..5d0be77
--- /dev/null
+++ b/arch/x86/kernel/tsc.c
@@ -0,0 +1,86 @@
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+
+unsigned int cpu_khz; /* TSC clocks / usec, not used here */
+EXPORT_SYMBOL(cpu_khz);
+unsigned int tsc_khz;
+EXPORT_SYMBOL(tsc_khz);
+
+/*
+ * TSC can be unstable due to cpufreq or due to unsynced TSCs
+ */
+int tsc_unstable;
+
+/* native_sched_clock() is called before tsc_init(), so
+ we must start with the TSC soft disabled to prevent
+ erroneous rdtsc usage on !cpu_has_tsc processors */
+int tsc_disabled = -1;
+
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ */
+u64 native_sched_clock(void)
+{
+ u64 this_offset;
+
+ /*
+ * Fall back to jiffies if there's no TSC available:
+ * ( But note that we still use it if the TSC is marked
+ * unstable. We do this because unlike Time Of Day,
+ * the scheduler clock tolerates small errors and it's
+ * very important for it to be as fast as the platform
+ * can achive it. )
+ */
+ if (unlikely(tsc_disabled)) {
+ /* No locking but a rare wrong value is not a big deal: */
+ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
+ }
+
+ /* read the Time Stamp Counter: */
+ rdtscll(this_offset);
+
+ /* return the value in ns */
+ return cycles_2_ns(this_offset);
+}
+
+/* We need to define a real function for sched_clock, to override the
+ weak default version */
+#ifdef CONFIG_PARAVIRT
+unsigned long long sched_clock(void)
+{
+ return paravirt_sched_clock();
+}
+#else
+unsigned long long
+sched_clock(void) __attribute__((alias("native_sched_clock")));
+#endif
+
+int check_tsc_unstable(void)
+{
+ return tsc_unstable;
+}
+EXPORT_SYMBOL_GPL(check_tsc_unstable);
+
+#ifdef CONFIG_X86_TSC
+int __init notsc_setup(char *str)
+{
+ printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
+ "cannot disable TSC completely.\n");
+ tsc_disabled = 1;
+ return 1;
+}
+#else
+/*
+ * disable flag for tsc. Takes effect by clearing the TSC cpu flag
+ * in cpu/common.c
+ */
+int __init notsc_setup(char *str)
+{
+ setup_clear_cpu_cap(X86_FEATURE_TSC);
+ return 1;
+}
+#endif
+
+__setup("notsc", notsc_setup);
diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c
index 6240922..dc89900 100644
--- a/arch/x86/kernel/tsc_32.c
+++ b/arch/x86/kernel/tsc_32.c
@@ -15,52 +15,8 @@
#include "mach_timer.h"
-/* native_sched_clock() is called before tsc_init(), so
- we must start with the TSC soft disabled to prevent
- erroneous rdtsc usage on !cpu_has_tsc processors */
-static int tsc_disabled = -1;
-
-/*
- * On some systems the TSC frequency does not
- * change with the cpu frequency. So we need
- * an extra value to store the TSC freq
- */
-unsigned int tsc_khz;
-EXPORT_SYMBOL_GPL(tsc_khz);
-
-#ifdef CONFIG_X86_TSC
-static int __init tsc_setup(char *str)
-{
- printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
- "cannot disable TSC completely.\n");
- tsc_disabled = 1;
- return 1;
-}
-#else
-/*
- * disable flag for tsc. Takes effect by clearing the TSC cpu flag
- * in cpu/common.c
- */
-static int __init tsc_setup(char *str)
-{
- setup_clear_cpu_cap(X86_FEATURE_TSC);
- return 1;
-}
-#endif
-
-__setup("notsc", tsc_setup);
-
-/*
- * code to mark and check if the TSC is unstable
- * due to cpufreq or due to unsynced TSCs
- */
-static int tsc_unstable;
-
-int check_tsc_unstable(void)
-{
- return tsc_unstable;
-}
-EXPORT_SYMBOL_GPL(check_tsc_unstable);
+extern int tsc_unstable;
+extern int tsc_disabled;
/* Accelerators for sched_clock()
* convert from cycles(64bits) => nanoseconds (64bits)
@@ -109,44 +65,6 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
local_irq_restore(flags);
}
-/*
- * Scheduler clock - returns current time in nanosec units.
- */
-unsigned long long native_sched_clock(void)
-{
- unsigned long long this_offset;
-
- /*
- * Fall back to jiffies if there's no TSC available:
- * ( But note that we still use it if the TSC is marked
- * unstable. We do this because unlike Time Of Day,
- * the scheduler clock tolerates small errors and it's
- * very important for it to be as fast as the platform
- * can achive it. )
- */
- if (unlikely(tsc_disabled))
- /* No locking but a rare wrong value is not a big deal: */
- return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
-
- /* read the Time Stamp Counter: */
- rdtscll(this_offset);
-
- /* return the value in ns */
- return cycles_2_ns(this_offset);
-}
-
-/* We need to define a real function for sched_clock, to override the
- weak default version */
-#ifdef CONFIG_PARAVIRT
-unsigned long long sched_clock(void)
-{
- return paravirt_sched_clock();
-}
-#else
-unsigned long long sched_clock(void)
- __attribute__((alias("native_sched_clock")));
-#endif
-
unsigned long native_calculate_cpu_khz(void)
{
unsigned long long start, end;
diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c
index 9898fb0..69cbe4c 100644
--- a/arch/x86/kernel/tsc_64.c
+++ b/arch/x86/kernel/tsc_64.c
@@ -13,12 +13,8 @@
#include <asm/timer.h>
#include <asm/vgtod.h>
-static int notsc __initdata = 0;
-
-unsigned int cpu_khz; /* TSC clocks / usec, not used here */
-EXPORT_SYMBOL(cpu_khz);
-unsigned int tsc_khz;
-EXPORT_SYMBOL(tsc_khz);
+extern int tsc_unstable;
+extern int tsc_disabled;
/* Accelerators for sched_clock()
* convert from cycles(64bits) => nanoseconds (64bits)
@@ -41,6 +37,7 @@ EXPORT_SYMBOL(tsc_khz);
*
* [email protected] "math is hard, lets go shopping!"
*/
+
DEFINE_PER_CPU(unsigned long, cyc2ns);
static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
@@ -63,41 +60,6 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
local_irq_restore(flags);
}
-unsigned long long native_sched_clock(void)
-{
- unsigned long a = 0;
-
- /* Could do CPU core sync here. Opteron can execute rdtsc speculatively,
- * which means it is not completely exact and may not be monotonous
- * between CPUs. But the errors should be too small to matter for
- * scheduling purposes.
- */
-
- rdtscll(a);
- return cycles_2_ns(a);
-}
-
-/* We need to define a real function for sched_clock, to override the
- weak default version */
-#ifdef CONFIG_PARAVIRT
-unsigned long long sched_clock(void)
-{
- return paravirt_sched_clock();
-}
-#else
-unsigned long long
-sched_clock(void) __attribute__((alias("native_sched_clock")));
-#endif
-
-
-static int tsc_unstable;
-
-int check_tsc_unstable(void)
-{
- return tsc_unstable;
-}
-EXPORT_SYMBOL_GPL(check_tsc_unstable);
-
#ifdef CONFIG_CPU_FREQ
/* Frequency scaling support. Adjust the TSC based timer when the cpu frequency
@@ -281,14 +243,6 @@ __cpuinit int unsynchronized_tsc(void)
return num_present_cpus() > 1;
}
-int __init notsc_setup(char *s)
-{
- notsc = 1;
- return 1;
-}
-
-__setup("notsc", notsc_setup);
-
static struct clocksource clocksource_tsc;
/*
@@ -346,12 +300,13 @@ EXPORT_SYMBOL_GPL(mark_tsc_unstable);
void __init init_tsc_clocksource(void)
{
- if (!notsc) {
- clocksource_tsc.mult = clocksource_khz2mult(tsc_khz,
- clocksource_tsc.shift);
- if (check_tsc_unstable())
- clocksource_tsc.rating = 0;
+ if (tsc_disabled > 0)
+ return;
- clocksource_register(&clocksource_tsc);
- }
+ clocksource_tsc.mult = clocksource_khz2mult(tsc_khz,
+ clocksource_tsc.shift);
+ if (check_tsc_unstable())
+ clocksource_tsc.rating = 0;
+
+ clocksource_register(&clocksource_tsc);
}