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Subject[patch 7/9] Adapt the time initialization code
We need to:
- initialize the RDTSCP instruction if available
- decide which hardware timer to use as MT (PM or HPET)
- decide what level of TSC->MT approximation to use
- none (as slow as the hardware MT can get) -- "notsc" option
- strictly monotonic (can't be done in a vsyscall) -- default
- unguaranteed monotonicity (very fast, vsyscall) -- "nomonotonic" option

Signed-off-by: Jiri Bohac <jbohac@suse.cz>

Index: linux-2.6.20-rc5/arch/x86_64/kernel/smpboot.c
===================================================================
--- linux-2.6.20-rc5.orig/arch/x86_64/kernel/smpboot.c
+++ linux-2.6.20-rc5/arch/x86_64/kernel/smpboot.c
@@ -318,6 +318,8 @@ static inline void set_cpu_sibling_map(i
}
}

+extern void time_initialize_cpu(void);
+
/*
* Setup code on secondary processor (after comming out of the trampoline)
*/
@@ -345,6 +347,7 @@ void __cpuinit start_secondary(void)
enable_NMI_through_LVT0(NULL);
enable_8259A_irq(0);
}
+ time_initialize_cpu();

enable_APIC_timer();

@@ -963,6 +966,8 @@ int __cpuinit __cpu_up(unsigned int cpu)
return err;
}

+extern void time_init_gtod(void);
+
/*
* Finish the SMP boot.
*/
Index: linux-2.6.20-rc5/arch/x86_64/kernel/time.c
===================================================================
--- linux-2.6.20-rc5.orig/arch/x86_64/kernel/time.c
+++ linux-2.6.20-rc5/arch/x86_64/kernel/time.c
@@ -968,6 +968,16 @@ static struct irqaction irq0 = {
timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL
};

+static void time_init_rdtsc(void)
+{
+ if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP)) {
+ int p;
+ p = smp_processor_id();
+ printk(KERN_INFO "Initializing RDTSCP feature on cpu %d.\n", p);
+ write_rdtscp_aux(p);
+ }
+}
+
void __init time_init(void)
{
if (nohpet)
@@ -979,27 +989,40 @@ void __init time_init(void)
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);

- if (!hpet_init())
- vxtime_hz = (FSEC_PER_SEC + hpet_period / 2) / hpet_period;
- else
- vxtime.hpet_address = 0;
+ /* decide what to use as Master Timer: HPET or PM? */
+ if (!hpet_init()) {
+ vxtime.mt_q = (hpet_period << 32) / FSEC_PER_NSEC;
+ mt_per_tick = hpet_use_timer ?
+ hpet_tick : LATCH * 12;
+ read_master_timer = read_master_timer_hpet;
+ timename = "HPET";
+ } else
+ if (pmtmr_ioport) {
+ vxtime.mt_q = (NSEC_PER_SEC << 32) / 916363636UL;
+ mt_per_tick = (LATCH * 3) << 8;
+ read_master_timer = read_master_timer_pm;
+ timename = "PM timer";
+ } else
+ panic("No suitable Master Timer found.\n");

- if (hpet_use_timer) {
- /* set tick_nsec to use the proper rate for HPET */
- tick_nsec = TICK_NSEC_HPET;
+ /* use PIT as main timer interrupt source if we can't use HPET */
+ if (hpet_use_timer)
cpu_khz = hpet_calibrate_tsc();
- timename = "HPET";
- } else {
+ else {
pit_init();
cpu_khz = pit_calibrate_tsc();
- timename = "PIT";
}

- vxtime.mode = VXTIME_TSC;
- vxtime.quot = (USEC_PER_SEC << US_SCALE) / vxtime_hz;
- vxtime.tsc_quot = (USEC_PER_MSEC << US_SCALE) / cpu_khz;
- vxtime.last_tsc = get_cycles_sync();
- set_cyc2ns_scale(cpu_khz);
+ /* initialize the master timer */
+ set_master_timer64(0);
+
+ /* initialize the timekeeping variables of the boot CPU */
+ vxtime.cpu[0].tsc_last = get_cycles_sync();
+ vxtime.cpu[0].mt_last = vxtime.cpu[0].mt_base = 0;
+ vxtime.cpu[0].tsc_slope = vxtime.cpu[0].tsc_slope_avg = (((USEC_PER_SEC << 32) / vxtime.mt_q) << TSC_SLOPE_SCALE) / cpu_khz;
+ time_init_rdtsc();
+
+ vxtime.mode = VXTIME_TSCS; /* not sure yet if CPUs have synced TSCs */
setup_irq(0, &irq0);

#ifndef CONFIG_SMP
@@ -1037,28 +1060,71 @@ __cpuinit int unsynchronized_tsc(void)
*/
void time_init_gtod(void)
{
- char *timetype;
-
- if (unsynchronized_tsc())
- notsc = 1;
+ char *tsc_method;

if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
vgetcpu_mode = VGETCPU_RDTSCP;
else
vgetcpu_mode = VGETCPU_LSL;

- timetype = hpet_use_timer ? "HPET/TSC" : "PIT/TSC";
+ if (notsc) {
+ tsc_method = "nothing";
+ vxtime.mode = VXTIME_MT;
+ }
+ else if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP)) {
+ if (nomonotonic) {
+ tsc_method = "RDTSCP";
+ vxtime.mode = VXTIME_TSCP;
+ }
+ else {
+ tsc_method = "RDTSCM (syscall)";
+ vxtime.mode = VXTIME_TSCM;
+ }
+ }
+ else {
+ tsc_method = "RDTSC";
vxtime.mode = VXTIME_TSC;
+#ifdef CONFIG_SMP
+ if (unsynchronized_tsc()) {
+ if (nomonotonic) {
+ tsc_method = "RDTSC (syscall)";
+ vxtime.mode = VXTIME_TSCS;
+ }
+ else {
+ tsc_method = "RDTSCM (syscall)";
+ vxtime.mode = VXTIME_TSCM;
+ }
+ }
+#endif
+ }
+

- printk(KERN_INFO "time.c: Using %ld.%06ld MHz WALL %s GTOD %s timer.\n",
- vxtime_hz / 1000000, vxtime_hz % 1000000, timename, timetype);
+ printk(KERN_INFO "time.c: Using %s as master timer, %s for time caching; vsyscall %s.\n",
+ timename, tsc_method, sysctl_vsyscall ? "enabled" : "disabled");
+ printk(KERN_INFO "time.c: Using %s as interrupt source.\n",
+ hpet_use_timer ? "HPET" : "PIT");
printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
- vxtime.quot = (USEC_PER_SEC << US_SCALE) / vxtime_hz;
- vxtime.tsc_quot = (USEC_PER_MSEC << US_SCALE) / cpu_khz;
- vxtime.last_tsc = get_cycles_sync();
+}

- set_cyc2ns_scale(cpu_khz);
+/*
+ * initialize the per_cpu timekeeping variables
+ * for non-boot CPUs
+ */
+void time_initialize_cpu(void *info)
+{
+ unsigned long flags;
+ int cpu = smp_processor_id();
+ u64 mt_now;
+ write_seqlock_irqsave(&xtime_lock, flags);
+ mt_now = get_master_timer64();
+ vxtime.cpu[cpu].tsc_last = get_cycles_sync();
+ vxtime.cpu[cpu].mt_last = mt_now;
+ vxtime.cpu[cpu].mt_base = mt_now;
+ vxtime.cpu[cpu].tsc_slope = vxtime.cpu[0].tsc_slope;
+ vxtime.cpu[cpu].tsc_slope_avg = vxtime.cpu[0].tsc_slope_avg;
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+ time_init_rdtsc();
}

__setup("report_lost_ticks", time_setup);
@@ -1098,19 +1164,38 @@ static int timer_resume(struct sys_devic
sleep_length = 0;
ctime = sleep_start;
}
- if (vxtime.hpet_address)
+
+ write_seqlock_irqsave(&xtime_lock,flags);
+
+ /* reenable the Master Timer */
+ if (read_master_timer == read_master_timer_hpet || hpet_use_timer)
hpet_reenable();
+ /* reenable PIT if used as main timer interrupt source */
else
i8254_timer_resume();

sec = ctime + clock_cmos_diff;
- write_seqlock_irqsave(&xtime_lock,flags);
xtime.tv_sec = sec;
xtime.tv_nsec = 0;
- vxtime.last_tsc = get_cycles_sync();
- write_sequnlock_irqrestore(&xtime_lock,flags);
+
+ /* re-initialize the master timer */
+ add_master_timer64(sleep_length * mt_per_tick);
+ vxtime.mt_wall += sleep_length * mt_per_tick;
+
jiffies += sleep_length;
- monotonic_base += sleep_length * (NSEC_PER_SEC/HZ);
+
+ /* re-initialize the timekeeping variables of the boot CPU */
+ vxtime.cpu[0].tsc_last = get_cycles_sync();
+ vxtime.cpu[0].mt_last = vxtime.cpu[0].mt_base = get_master_timer64();
+ /* FIXME: what speed does the cpu really start at; I doubt cpu_khz is right at this point ??!!!
+ And what speed do the non-boot cpus start at? Their timekeeping variables will probably be set wrong
+ by copying from CPU 0 in time_initialize_cpu(); Not a great deal, as they will be synced somehow,
+ but not exactly nice -JB */
+ vxtime.cpu[0].tsc_slope = vxtime.cpu[0].tsc_slope_avg =
+ (((USEC_PER_SEC << 32) / vxtime.mt_q) << TSC_SLOPE_SCALE) / cpu_khz;
+
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
touch_softlockup_watchdog();
return 0;
}
@@ -1402,3 +1487,11 @@ int __init notsc_setup(char *s)
}

__setup("notsc", notsc_setup);
+
+int __init nomonotonic_setup(char *s)
+{
+ nomonotonic = 1;
+ return 1;
+}
+
+__setup("nomonotonic", nomonotonic_setup);
Index: linux-2.6.20-rc5/include/linux/time.h
===================================================================
--- linux-2.6.20-rc5.orig/include/linux/time.h
+++ linux-2.6.20-rc5/include/linux/time.h
@@ -31,6 +31,7 @@ struct timezone {
#define MSEC_PER_SEC 1000L
#define USEC_PER_MSEC 1000L
#define NSEC_PER_USEC 1000L
+#define FSEC_PER_NSEC 1000000L
#define NSEC_PER_MSEC 1000000L
#define USEC_PER_SEC 1000000L
#define NSEC_PER_SEC 1000000000L
--
-
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