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[PATCH] x86_64: Make use of the *PER* constants in time.c
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This patch makes use of the newly added conversion constants
in time.h to x86-64 time.c. The code gets significantly easier
to understand.

Signed-off-by: Vojtech Pavlik <[email protected]>
Signed-off-by: Andi Kleen <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Vojtech Pavlik authored and Linus Torvalds committed Jun 26, 2006
1 parent e30db3e commit 4221133
Showing 1 changed file with 35 additions and 28 deletions.
63 changes: 35 additions & 28 deletions arch/x86_64/kernel/time.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,13 @@ DEFINE_SPINLOCK(i8253_lock);
int nohpet __initdata = 0;
static int notsc __initdata = 0;

#define USEC_PER_TICK (USEC_PER_SEC / HZ)
#define NSEC_PER_TICK (NSEC_PER_SEC / HZ)
#define FSEC_PER_TICK (FSEC_PER_SEC / HZ)

#define NS_SCALE 10 /* 2^10, carefully chosen */
#define US_SCALE 32 /* 2^32, arbitralrily chosen */

unsigned int cpu_khz; /* TSC clocks / usec, not used here */
static unsigned long hpet_period; /* fsecs / HPET clock */
unsigned long hpet_tick; /* HPET clocks / interrupt */
Expand Down Expand Up @@ -88,15 +95,15 @@ static inline unsigned int do_gettimeoffset_tsc(void)
t = get_cycles_sync();
if (t < vxtime.last_tsc)
t = vxtime.last_tsc; /* hack */
x = ((t - vxtime.last_tsc) * vxtime.tsc_quot) >> 32;
x = ((t - vxtime.last_tsc) * vxtime.tsc_quot) >> US_SCALE;
return x;
}

static inline unsigned int do_gettimeoffset_hpet(void)
{
/* cap counter read to one tick to avoid inconsistencies */
unsigned long counter = hpet_readl(HPET_COUNTER) - vxtime.last;
return (min(counter,hpet_tick) * vxtime.quot) >> 32;
return (min(counter,hpet_tick) * vxtime.quot) >> US_SCALE;
}

unsigned int (*do_gettimeoffset)(void) = do_gettimeoffset_tsc;
Expand All @@ -116,7 +123,7 @@ void do_gettimeofday(struct timeval *tv)
seq = read_seqbegin(&xtime_lock);

sec = xtime.tv_sec;
usec = xtime.tv_nsec / 1000;
usec = xtime.tv_nsec / NSEC_PER_USEC;

/* i386 does some correction here to keep the clock
monotonous even when ntpd is fixing drift.
Expand All @@ -127,14 +134,14 @@ void do_gettimeofday(struct timeval *tv)
in arch/x86_64/kernel/vsyscall.c and export all needed
variables in vmlinux.lds. -AK */

t = (jiffies - wall_jiffies) * (1000000L / HZ) +
t = (jiffies - wall_jiffies) * USEC_PER_TICK +
do_gettimeoffset();
usec += t;

} while (read_seqretry(&xtime_lock, seq));

tv->tv_sec = sec + usec / 1000000;
tv->tv_usec = usec % 1000000;
tv->tv_sec = sec + usec / USEC_PER_SEC;
tv->tv_usec = usec % USEC_PER_SEC;
}

EXPORT_SYMBOL(do_gettimeofday);
Expand All @@ -155,8 +162,8 @@ int do_settimeofday(struct timespec *tv)

write_seqlock_irq(&xtime_lock);

nsec -= do_gettimeoffset() * 1000 +
(jiffies - wall_jiffies) * (NSEC_PER_SEC/HZ);
nsec -= do_gettimeoffset() * NSEC_PER_USEC +
(jiffies - wall_jiffies) * NSEC_PER_TICK;

wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
Expand Down Expand Up @@ -286,7 +293,7 @@ unsigned long long monotonic_clock(void)
this_offset = hpet_readl(HPET_COUNTER);
} while (read_seqretry(&xtime_lock, seq));
offset = (this_offset - last_offset);
offset *= (NSEC_PER_SEC/HZ) / hpet_tick;
offset *= NSEC_PER_TICK / hpet_tick;
} else {
do {
seq = read_seqbegin(&xtime_lock);
Expand All @@ -295,7 +302,8 @@ unsigned long long monotonic_clock(void)
base = monotonic_base;
} while (read_seqretry(&xtime_lock, seq));
this_offset = get_cycles_sync();
offset = (this_offset - last_offset)*1000 / cpu_khz;
/* FIXME: 1000 or 1000000? */
offset = (this_offset - last_offset)*1000 / cpu_khz;
}
return base + offset;
}
Expand Down Expand Up @@ -380,7 +388,7 @@ void main_timer_handler(struct pt_regs *regs)
}

monotonic_base +=
(offset - vxtime.last)*(NSEC_PER_SEC/HZ) / hpet_tick;
(offset - vxtime.last) * NSEC_PER_TICK / hpet_tick;

vxtime.last = offset;
#ifdef CONFIG_X86_PM_TIMER
Expand All @@ -389,24 +397,25 @@ void main_timer_handler(struct pt_regs *regs)
#endif
} else {
offset = (((tsc - vxtime.last_tsc) *
vxtime.tsc_quot) >> 32) - (USEC_PER_SEC / HZ);
vxtime.tsc_quot) >> US_SCALE) - USEC_PER_TICK;

if (offset < 0)
offset = 0;

if (offset > (USEC_PER_SEC / HZ)) {
lost = offset / (USEC_PER_SEC / HZ);
offset %= (USEC_PER_SEC / HZ);
if (offset > USEC_PER_TICK) {
lost = offset / USEC_PER_TICK;
offset %= USEC_PER_TICK;
}

monotonic_base += (tsc - vxtime.last_tsc)*1000000/cpu_khz ;
/* FIXME: 1000 or 1000000? */
monotonic_base += (tsc - vxtime.last_tsc) * 1000000 / cpu_khz;

vxtime.last_tsc = tsc - vxtime.quot * delay / vxtime.tsc_quot;

if ((((tsc - vxtime.last_tsc) *
vxtime.tsc_quot) >> 32) < offset)
vxtime.tsc_quot) >> US_SCALE) < offset)
vxtime.last_tsc = tsc -
(((long) offset << 32) / vxtime.tsc_quot) - 1;
(((long) offset << US_SCALE) / vxtime.tsc_quot) - 1;
}

if (lost > 0) {
Expand Down Expand Up @@ -466,16 +475,15 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
}

static unsigned int cyc2ns_scale __read_mostly;
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */

static inline void set_cyc2ns_scale(unsigned long cpu_khz)
{
cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
cyc2ns_scale = (NSEC_PER_MSEC << NS_SCALE) / cpu_khz;
}

static inline unsigned long long cycles_2_ns(unsigned long long cyc)
{
return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
return (cyc * cyc2ns_scale) >> NS_SCALE;
}

unsigned long long sched_clock(void)
Expand All @@ -488,7 +496,7 @@ unsigned long long sched_clock(void)
Disadvantage is a small drift between CPUs in some configurations,
but that should be tolerable. */
if (__vxtime.mode == VXTIME_HPET)
return (hpet_readl(HPET_COUNTER) * vxtime.quot) >> 32;
return (hpet_readl(HPET_COUNTER) * vxtime.quot) >> US_SCALE;
#endif

/* Could do CPU core sync here. Opteron can execute rdtsc speculatively,
Expand Down Expand Up @@ -631,7 +639,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,

cpu_khz = cpufreq_scale(cpu_khz_ref, ref_freq, freq->new);
if (!(freq->flags & CPUFREQ_CONST_LOOPS))
vxtime.tsc_quot = (1000L << 32) / cpu_khz;
vxtime.tsc_quot = (USEC_PER_MSEC << US_SCALE) / cpu_khz;
}

set_cyc2ns_scale(cpu_khz_ref);
Expand Down Expand Up @@ -823,8 +831,7 @@ static int hpet_init(void)
if (hpet_period < 100000 || hpet_period > 100000000)
return -1;

hpet_tick = (1000000000L * (USEC_PER_SEC / HZ) + hpet_period / 2) /
hpet_period;
hpet_tick = (FSEC_PER_TICK + hpet_period / 2) / hpet_period;

hpet_use_timer = (id & HPET_ID_LEGSUP);

Expand Down Expand Up @@ -898,7 +905,7 @@ void __init time_init(void)
-xtime.tv_sec, -xtime.tv_nsec);

if (!hpet_init())
vxtime_hz = (1000000000000000L + hpet_period / 2) / hpet_period;
vxtime_hz = (FSEC_PER_SEC + hpet_period / 2) / hpet_period;
else
vxtime.hpet_address = 0;

Expand Down Expand Up @@ -927,8 +934,8 @@ void __init time_init(void)
vxtime_hz / 1000000, vxtime_hz % 1000000, timename, gtod);
printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
vxtime.quot = (1000000L << 32) / vxtime_hz;
vxtime.tsc_quot = (1000L << 32) / cpu_khz;
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();
setup_irq(0, &irq0);

Expand Down

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