[PATCH] x86_64: Don't try to synchronize the TSC over CPUs on Intel CPUs at boot.
They already do this in hardware and the Linux algorithm actually adds errors. Cc: mingo@elte.hu Cc: rohit.seth@intel.com Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
parent
3c02175113
commit
737c5c3bde
|
@ -335,7 +335,13 @@ static __cpuinit void sync_tsc(unsigned int master)
|
|||
|
||||
static void __cpuinit tsc_sync_wait(void)
|
||||
{
|
||||
if (notscsync || !cpu_has_tsc)
|
||||
/*
|
||||
* When the CPU has synchronized TSCs assume the BIOS
|
||||
* or the hardware already synced. Otherwise we could
|
||||
* mess up a possible perfect synchronization with a
|
||||
* not-quite-perfect algorithm.
|
||||
*/
|
||||
if (notscsync || !cpu_has_tsc || !unsynchronized_tsc())
|
||||
return;
|
||||
sync_tsc(0);
|
||||
}
|
||||
|
|
|
@ -953,7 +953,7 @@ void __init time_init(void)
|
|||
* Make an educated guess if the TSC is trustworthy and synchronized
|
||||
* over all CPUs.
|
||||
*/
|
||||
static __init int unsynchronized_tsc(void)
|
||||
__init int unsynchronized_tsc(void)
|
||||
{
|
||||
#ifdef CONFIG_SMP
|
||||
if (oem_force_hpet_timer())
|
||||
|
@ -964,7 +964,7 @@ static __init int unsynchronized_tsc(void)
|
|||
return 0;
|
||||
#endif
|
||||
/* Assume multi socket systems are not synchronized */
|
||||
return num_online_cpus() > 1;
|
||||
return num_present_cpus() > 1;
|
||||
}
|
||||
|
||||
/*
|
||||
|
|
|
@ -89,6 +89,8 @@ extern void check_efer(void);
|
|||
|
||||
extern int unhandled_signal(struct task_struct *tsk, int sig);
|
||||
|
||||
extern int unsynchronized_tsc(void);
|
||||
|
||||
extern void select_idle_routine(const struct cpuinfo_x86 *c);
|
||||
|
||||
extern void gart_parse_options(char *);
|
||||
|
|
Loading…
Reference in a new issue