[PATCH] dyn-tick3 tweaks respin

Con Kolivas
2005-08-05T03:24:39Z

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On Fri, 5 Aug 2005 11:39 am, Con Kolivas wrote:
> On Fri, 5 Aug 2005 10:53 am, Nick Piggin wrote:
> > All else being equal, it is much better if you unlock in the
> > same function that takes the lock. For readability.
> >
> > It looks like you should be able to leave all the flow control
> > and locking the same, and use update_monotonic_base() to
> > do the actual update?
>
> Good advice, thanks. Will respin.

Like this I assume you meant?

Cheers,
Con
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Index: linux-2.6.13-rc5-ck2/arch/i386/kernel/timers/timer_tsc.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/timers/timer_tsc.c 2005-08-03 11:29:29.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/timers/timer_tsc.c 2005-08-05 13:15:23.000000000 +1000
@@ -167,10 +167,19 @@ static void delay_tsc(unsigned long loop
} while ((now-bclock) < loops);
}

+/* update the monotonic base value */
+static inline void update_monotonic_base(unsigned long long last_offset)
+{
+ unsigned long long this_offset;
+
+ this_offset = ((unsigned long long)last_tsc_high << 32) | last_tsc_low;
+ monotonic_base += cycles_2_ns(this_offset - last_offset);
+}
+
#ifdef CONFIG_HPET_TIMER
static void mark_offset_tsc_hpet(void)
{
- unsigned long long this_offset, last_offset;
+ unsigned long long last_offset;
unsigned long offset, temp, hpet_current;

write_seqlock(&monotonic_lock);
@@ -198,9 +207,7 @@ static void mark_offset_tsc_hpet(void)
}
hpet_last = hpet_current;

- /* update the monotonic base value */
- this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
- monotonic_base += cycles_2_ns(this_offset - last_offset);
+ update_monotonic_base(last_offset);
write_sequnlock(&monotonic_lock);

/* calculate delay_at_last_interrupt */
@@ -347,7 +354,7 @@ static void mark_offset_tsc(void)
int count;
int countmp;
static int count1 = 0;
- unsigned long long this_offset, last_offset;
+ unsigned long long last_offset;
static int lost_count = 0;

write_seqlock(&monotonic_lock);
@@ -368,8 +375,11 @@ static void mark_offset_tsc(void)

rdtsc(last_tsc_low, last_tsc_high);

- if (dyn_tick_enabled())
- goto monotonic_base;
+ if (dyn_tick_enabled()) {
+ update_monotonic_base(last_offset);
+ write_sequnlock(&monotonic_lock);
+ return;
+ }

spin_lock(&i8253_lock);
outb_p(0x00, PIT_MODE); /* latch the count ASAP */
@@ -439,16 +449,9 @@ static void mark_offset_tsc(void)
} else
lost_count = 0;

- monotonic_base:
-
- /* update the monotonic base value */
- this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
- monotonic_base += cycles_2_ns(this_offset - last_offset);
+ update_monotonic_base(last_offset);
write_sequnlock(&monotonic_lock);

- if (dyn_tick_enabled())
- return;
-
/* calculate delay_at_last_interrupt */
count = ((LATCH-1) - count) * TICK_SIZE;
delay_at_last_interrupt = (count + LATCH/2) / LATCH;