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Commit 0ef95533 authored by Alok Kataria's avatar Alok Kataria Committed by Ingo Molnar
Browse files

x86: merge sched_clock handling 



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: default avatarAlok N Kataria <akataria@vmware.com>
Signed-off-by: default avatarDan Hecht <dhecht@vmware.com>
Cc: Dan Hecht <dhecht@vmware.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 746f2eb7

arch/x86/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ 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

arch/x86/kernel/time_32.c

+0 −3
Original line number Diff line number Diff line
@@ -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)

arch/x86/kernel/tsc.c

0 → 100644
+86 −0
Original line number Diff line number Diff line 
#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);

arch/x86/kernel/tsc_32.c

+2 −84
Original line number Diff line number Diff line
@@ -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;

arch/x86/kernel/tsc_64.c

+11 −56
Original line number Diff line number Diff line
@@ -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); 
 *

 *			-johnstul@us.ibm.com "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;



/*
@@ -346,7 +300,9 @@ EXPORT_SYMBOL_GPL(mark_tsc_unstable); 


void __init init_tsc_clocksource(void)

{

	if (!notsc) {

	if (tsc_disabled > 0)

		return;



	clocksource_tsc.mult = clocksource_khz2mult(tsc_khz,

			clocksource_tsc.shift);

	if (check_tsc_unstable())
@@ -354,4 +310,3 @@ void __init init_tsc_clocksource(void) 


	clocksource_register(&clocksource_tsc);

}
 
}