kernel-ark/arch/x86/include/asm/tsc.h
Suresh Siddha 28a00184be x86, tsc: Skip TSC synchronization checks for tsc=reliable
tsc=reliable boot parameter is supposed to skip all the TSC
stablility checks during boot time.

On a 8-socket system where we want to run an experiment with the
"tsc=reliable" boot option, TSC synchronization checks are not
getting skipped and marking the TSC as not stable.

Check for tsc_clocksource_reliable (which is set via
tsc=reliable or for platforms supporting synthetic TSC_RELIABLE
feature bit etc) and when set, skip the TSC synchronization
tests during boot.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1320446537.15071.14.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-05 18:00:31 +01:00

68 lines
1.4 KiB
C

/*
* x86 TSC related functions
*/
#ifndef _ASM_X86_TSC_H
#define _ASM_X86_TSC_H
#include <asm/processor.h>
#define NS_SCALE 10 /* 2^10, carefully chosen */
#define US_SCALE 32 /* 2^32, arbitralrily chosen */
/*
* Standard way to access the cycle counter.
*/
typedef unsigned long long cycles_t;
extern unsigned int cpu_khz;
extern unsigned int tsc_khz;
extern void disable_TSC(void);
static inline cycles_t get_cycles(void)
{
unsigned long long ret = 0;
#ifndef CONFIG_X86_TSC
if (!cpu_has_tsc)
return 0;
#endif
rdtscll(ret);
return ret;
}
static __always_inline cycles_t vget_cycles(void)
{
/*
* We only do VDSOs on TSC capable CPUs, so this shouldn't
* access boot_cpu_data (which is not VDSO-safe):
*/
#ifndef CONFIG_X86_TSC
if (!cpu_has_tsc)
return 0;
#endif
return (cycles_t)__native_read_tsc();
}
extern void tsc_init(void);
extern void mark_tsc_unstable(char *reason);
extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern unsigned long native_calibrate_tsc(void);
extern int tsc_clocksource_reliable;
/*
* Boot-time check whether the TSCs are synchronized across
* all CPUs/cores:
*/
extern void check_tsc_sync_source(int cpu);
extern void check_tsc_sync_target(void);
extern int notsc_setup(char *);
extern void save_sched_clock_state(void);
extern void restore_sched_clock_state(void);
#endif /* _ASM_X86_TSC_H */