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Add a CPU local timer based on the LAPIC. This is consistently faster

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than TSC, but doesn't suffer from SpeedStep as TSC does.

The default quality is higher than HPET for UP, but -100 for
MULTIPROCESSOR as it needs CPU local state which doesn't exist yet.
This commit is contained in:
joerg 2007-12-03 22:17:27 +00:00
parent 27f20ecf58
commit e5784d23f1
3 changed files with 70 additions and 4 deletions
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3
sys/arch/amd64/include/cpu.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: cpu.h,v 1.33 2007/11/22 16:16:45 bouyer Exp $ */
/* $NetBSD: cpu.h,v 1.34 2007/12/03 22:17:27 joerg Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
@ -120,6 +120,7 @@ struct cpu_info {
uint32_t ci_feature2_flags;
uint32_t ci_vendor[4]; /* vendor string */
u_int64_t ci_tsc_freq;
volatile uint32_t ci_lapic_counter;
const struct cpu_functions *ci_func;
void (*cpu_setup)(struct cpu_info *);

3
sys/arch/i386/include/cpu.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: cpu.h,v 1.150 2007/10/29 01:35:36 ad Exp $ */
/* $NetBSD: cpu.h,v 1.151 2007/12/03 22:17:28 joerg Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
@ -133,6 +133,7 @@ struct cpu_info {
uint32_t ci_vendor[4]; /* vendor string */
uint32_t ci_cpu_serial[3]; /* PIII serial number */
uint64_t ci_tsc_freq; /* cpu cycles/second */
volatile uint32_t ci_lapic_counter;
const struct cpu_functions *ci_func; /* start/stop functions */
void (*cpu_setup)(struct cpu_info *);

68
sys/arch/x86/x86/lapic.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: lapic.c,v 1.27 2007/11/14 15:54:22 joerg Exp $ */
/* $NetBSD: lapic.c,v 1.28 2007/12/03 22:17:28 joerg Exp $ */
/*-
* Copyright (c) 2000 The NetBSD Foundation, Inc.
@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: lapic.c,v 1.27 2007/11/14 15:54:22 joerg Exp $");
__KERNEL_RCSID(0, "$NetBSD: lapic.c,v 1.28 2007/12/03 22:17:28 joerg Exp $");
#include "opt_ddb.h"
#include "opt_mpbios.h" /* for MPDEBUG */
@ -239,6 +239,60 @@ uint32_t lapic_frac_usec_per_cycle;
uint64_t lapic_frac_cycle_per_usec;
uint32_t lapic_delaytab[26];
static u_int
lapic_get_timecount(struct timecounter *tc)
{
struct cpu_info *ci;
uint32_t cur_timer;
int s;
s = splhigh();
ci = curcpu();
/*
* Check for a race against the clockinterrupt.
* The update of ci_lapic_counter is blocked by splhigh() and
* the check for a pending clockinterrupt compensates for that.
*
* If the current tick is almost the Initial Counter, explicitly
* check for the pending interrupt bit as the interrupt delivery
* could be asynchronious and compensate as well.
*
* This can't be done without splhigh() as the calling code might
* have masked the clockinterrupt already.
*
* This code assumes that clockinterrupts are not missed.
*/
cur_timer = lapic_gettick();
if (cur_timer >= lapic_tval - 1) {
uint16_t reg = LAPIC_IRR + LAPIC_TIMER_VECTOR / 32 * 16;
if (i82489_readreg(reg) & (1 << (LAPIC_TIMER_VECTOR % 32))) {
cur_timer -= lapic_tval;
}
} else if (ci->ci_istate.ipending & (1 << LIR_TIMER))
cur_timer = lapic_gettick() - lapic_tval;
cur_timer = ci->ci_lapic_counter - cur_timer;
splx(s);
return cur_timer;
}
static struct timecounter lapic_timecounter = {
lapic_get_timecount,
NULL,
~0u,
0,
"lapic",
#ifndef MULTIPROCESSOR
2100,
#else
-100, /* per CPU state */
#endif
NULL,
NULL,
};
extern u_int i8254_get_timecount(struct timecounter *);
void
@ -253,6 +307,7 @@ lapic_clockintr(void *arg, struct intrframe *frame)
#endif /* TIMECOUNTER_DEBUG && __HAVE_TIMECOUNTER */
struct cpu_info *ci = curcpu();
ci->ci_lapic_counter += lapic_tval;
ci->ci_isources[LIR_TIMER]->is_evcnt.ev_count++;
#if defined(TIMECOUNTER_DEBUG)
@ -448,6 +503,15 @@ lapic_calibrate_timer(struct cpu_info *ci)
delay_func = lapic_delay;
initclock_func = lapic_initclocks;
initrtclock(0);
if (lapic_timecounter.tc_frequency == 0) {
/*
* Hook up time counter.
* This assume that all LAPICs have the same frequency.
*/
lapic_timecounter.tc_frequency = lapic_per_second;
tc_init(&lapic_timecounter);
}
}
}