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-rw-r--r--arch/ia64/kernel/time.c120
1 files changed, 66 insertions, 54 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index b88855ce4..d14ba0031 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -34,7 +34,10 @@ unsigned long last_cli_ip;
static struct {
unsigned long delta;
- unsigned long next[NR_CPUS];
+ union {
+ unsigned long count;
+ unsigned char pad[SMP_CACHE_BYTES];
+ } next[NR_CPUS];
} itm;
static void
@@ -69,16 +72,27 @@ do_profile (unsigned long ip)
static inline unsigned long
gettimeoffset (void)
{
- unsigned long now = ia64_get_itc();
- unsigned long elapsed_cycles, lost;
-
- elapsed_cycles = now - (itm.next[smp_processor_id()] - itm.delta);
-
- lost = lost_ticks;
- if (lost)
- elapsed_cycles += lost*itm.delta;
-
+#ifdef CONFIG_SMP
+ /*
+ * The code below doesn't work for SMP because only CPU 0
+ * keeps track of the time.
+ */
+ return 0;
+#else
+ unsigned long now = ia64_get_itc(), last_tick;
+ unsigned long elapsed_cycles, lost = lost_ticks;
+
+ last_tick = (itm.next[smp_processor_id()].count - (lost+1)*itm.delta);
+# if 1
+ if ((long) (now - last_tick) < 0) {
+ printk("Yikes: now < last_tick (now=0x%lx,last_tick=%lx)! No can do.\n",
+ now, last_tick);
+ return 0;
+ }
+# endif
+ elapsed_cycles = now - last_tick;
return (elapsed_cycles*my_cpu_data.usec_per_cyc) >> IA64_USEC_PER_CYC_SHIFT;
+#endif
}
void
@@ -137,6 +151,7 @@ timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
static unsigned long last_time;
static unsigned char count;
int cpu = smp_processor_id();
+ unsigned long new_itm;
int printed = 0;
/*
@@ -146,6 +161,12 @@ timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
* xtime_lock.
*/
write_lock(&xtime_lock);
+ new_itm = itm.next[cpu].count;
+
+ if (!time_after(ia64_get_itc(), new_itm))
+ printk("Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
+ ia64_get_itc(), new_itm);
+
while (1) {
/*
* Do kernel PC profiling here. We multiply the
@@ -164,18 +185,10 @@ timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
do_timer(regs);
#endif
- itm.next[cpu] += itm.delta;
- /*
- * There is a race condition here: to be on the "safe"
- * side, we process timer ticks until itm.next is
- * ahead of the itc by at least half the timer
- * interval. This should give us enough time to set
- * the new itm value without losing a timer tick.
- */
- if (time_after(itm.next[cpu], ia64_get_itc() + itm.delta/2)) {
- ia64_set_itm(itm.next[cpu]);
+ new_itm += itm.delta;
+ itm.next[cpu].count = new_itm;
+ if (time_after(new_itm, ia64_get_itc()))
break;
- }
#if !(defined(CONFIG_IA64_SOFTSDV_HACKS) && defined(CONFIG_SMP))
/*
@@ -188,28 +201,39 @@ timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
last_time = jiffies;
if (!printed) {
printk("Lost clock tick on CPU %d (now=%lx, next=%lx)!!\n",
- cpu, ia64_get_itc(), itm.next[cpu]);
+ cpu, ia64_get_itc(), itm.next[cpu].count);
printed = 1;
- }
# ifdef CONFIG_IA64_DEBUG_IRQ
- printk("last_cli_ip=%lx\n", last_cli_ip);
+ printk("last_cli_ip=%lx\n", last_cli_ip);
# endif
+ }
}
#endif
}
write_unlock(&xtime_lock);
+
+ /*
+ * If we're too close to the next clock tick for comfort, we
+ * increase the saftey margin by intentionally dropping the
+ * next tick(s). We do NOT update itm.next accordingly
+ * because that would force us to call do_timer() which in
+ * turn would let our clock run too fast (with the potentially
+ * devastating effect of losing monotony of time).
+ */
+ while (!time_after(new_itm, ia64_get_itc() + itm.delta/2))
+ new_itm += itm.delta;
+ ia64_set_itm(new_itm);
}
-#ifdef CONFIG_ITANIUM_ASTEP_SPECIFIC
+#if defined(CONFIG_ITANIUM_ASTEP_SPECIFIC) || defined(CONFIG_IA64_SOFTSDV_HACKS)
-void
+/*
+ * Interrupts must be disabled before calling this routine.
+ */
+void
ia64_reset_itm (void)
{
- unsigned long flags;
-
- local_irq_save(flags);
timer_interrupt(0, 0, ia64_task_regs(current));
- local_irq_restore(flags);
}
#endif /* CONFIG_ITANIUM_ASTEP_SPECIFIC */
@@ -220,11 +244,14 @@ ia64_reset_itm (void)
void __init
ia64_cpu_local_tick(void)
{
+#ifdef CONFIG_IA64_SOFTSDV_HACKS
+ ia64_set_itc(0);
+#endif
+
/* arrange for the cycle counter to generate a timer interrupt: */
ia64_set_itv(TIMER_IRQ, 0);
- ia64_set_itc(0);
- itm.next[smp_processor_id()] = ia64_get_itc() + itm.delta;
- ia64_set_itm(itm.next[smp_processor_id()]);
+ itm.next[smp_processor_id()].count = ia64_get_itc() + itm.delta;
+ ia64_set_itm(itm.next[smp_processor_id()].count);
}
void __init
@@ -254,25 +281,7 @@ ia64_init_itm (void)
itc_ratio.num = 3;
itc_ratio.den = 1;
}
-#if defined(CONFIG_IA64_LION_HACKS)
- /* Our Lion currently returns base freq 104.857MHz, which
- ain't right (it really is 100MHz). */
- printk("SAL/PAL returned: base-freq=%lu, itc-ratio=%lu/%lu, proc-ratio=%lu/%lu\n",
- platform_base_freq, itc_ratio.num, itc_ratio.den,
- proc_ratio.num, proc_ratio.den);
- platform_base_freq = 100000000;
-#elif 0 && defined(CONFIG_IA64_BIGSUR_HACKS)
- /* BigSur with 991020 firmware returned itc-ratio=9/2 and base
- freq 75MHz, which wasn't right. The 991119 firmware seems
- to return the right values, so this isn't necessary
- anymore... */
- printk("SAL/PAL returned: base-freq=%lu, itc-ratio=%lu/%lu, proc-ratio=%lu/%lu\n",
- platform_base_freq, itc_ratio.num, itc_ratio.den,
- proc_ratio.num, proc_ratio.den);
- platform_base_freq = 100000000;
- proc_ratio.num = 5; proc_ratio.den = 1;
- itc_ratio.num = 5; itc_ratio.den = 1;
-#elif defined(CONFIG_IA64_SOFTSDV_HACKS)
+#ifdef CONFIG_IA64_SOFTSDV_HACKS
platform_base_freq = 10000000;
proc_ratio.num = 4; proc_ratio.den = 1;
itc_ratio.num = 4; itc_ratio.den = 1;
@@ -290,8 +299,9 @@ ia64_init_itm (void)
itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
itm.delta = itc_freq / HZ;
- printk("timer: base freq=%lu.%03luMHz, ITC ratio=%lu/%lu, ITC freq=%lu.%03luMHz\n",
- platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
+ printk("timer: CPU %d base freq=%lu.%03luMHz, ITC ratio=%lu/%lu, ITC freq=%lu.%03luMHz\n",
+ smp_processor_id(),
+ platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
my_cpu_data.proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
@@ -313,6 +323,8 @@ void __init
time_init (void)
{
/* we can't do request_irq() here because the kmalloc() would fail... */
+ irq_desc[TIMER_IRQ].status |= IRQ_PER_CPU;
+ irq_desc[TIMER_IRQ].handler = &irq_type_ia64_sapic;
setup_irq(TIMER_IRQ, &timer_irqaction);
efi_gettimeofday(&xtime);
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-13 01:47:31 +0000