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make loop counter volatile to prevent gcc4.1 from optimizing away entire loop body
[pintos-anon]
/
src
/
devices
/
timer.c
diff --git
a/src/devices/timer.c
b/src/devices/timer.c
index 9e1b4989c833b62cfcaa5a66032c1cae1124fec0..070c487328a61e10a8e6a86390703f4dd289173b 100644
(file)
--- a/
src/devices/timer.c
+++ b/
src/devices/timer.c
@@
-16,9
+16,6
@@
#error TIMER_FREQ <= 1000 recommended
#endif
#error TIMER_FREQ <= 1000 recommended
#endif
-/* Number of time ticks to elapse between process yields. */
-#define TIME_SLICE 1
-
/* Number of timer ticks since OS booted. */
static volatile int64_t ticks;
/* Number of timer ticks since OS booted. */
static volatile int64_t ticks;
@@
-45,7
+42,7
@@
timer_init (void)
outb (0x40, count & 0xff);
outb (0x40, count >> 8);
outb (0x40, count & 0xff);
outb (0x40, count >> 8);
- intr_register
(0x20, 0, INTR_OFF
, timer_interrupt, "8254 Timer");
+ intr_register
_ext (0x20
, timer_interrupt, "8254 Timer");
}
/* Calibrates loops_per_tick, used to implement brief delays. */
}
/* Calibrates loops_per_tick, used to implement brief delays. */
@@
-126,7
+123,7
@@
timer_nsleep (int64_t ns)
void
timer_print_stats (void)
{
void
timer_print_stats (void)
{
- printf ("Timer: %"PRId64" ticks\n", ti
cks
);
+ printf ("Timer: %"PRId64" ticks\n", ti
mer_ticks ()
);
}
\f
/* Timer interrupt handler. */
}
\f
/* Timer interrupt handler. */
@@
-135,8
+132,6
@@
timer_interrupt (struct intr_frame *args UNUSED)
{
ticks++;
thread_tick ();
{
ticks++;
thread_tick ();
- if (ticks % TIME_SLICE == 0)
- intr_yield_on_return ();
}
/* Returns true if LOOPS iterations waits for more than one timer
}
/* Returns true if LOOPS iterations waits for more than one timer
@@
-167,7
+162,7
@@
too_many_loops (unsigned loops)
differently in different places the results would be difficult
to predict. */
static void NO_INLINE
differently in different places the results would be difficult
to predict. */
static void NO_INLINE
-busy_wait (int64_t loops)
+busy_wait (
volatile
int64_t loops)
{
while (loops-- > 0)
continue;
{
while (loops-- > 0)
continue;