Re: [PATCH 11/13] Time: x86-64 Conversion to Generic Timekeeping
From: Ingo Molnar
Date: Sat Nov 26 2005 - 09:57:20 EST
- clean up timeofday-arch-x86-64-part1.patch
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
arch/x86_64/kernel/time.c | 91 ++++++++++++++++++++++--------------------
arch/x86_64/kernel/vsyscall.c | 45 ++++++++++++--------
2 files changed, 75 insertions(+), 61 deletions(-)
Index: linux/arch/x86_64/kernel/time.c
===================================================================
--- linux.orig/arch/x86_64/kernel/time.c
+++ linux/arch/x86_64/kernel/time.c
@@ -42,6 +42,8 @@
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/apic.h>
#endif
+#include <linux/clocksource.h>
+#include <asm/vsyscall.h>
extern void i8254_timer_resume(void);
extern int using_apic_timer;
@@ -251,9 +253,10 @@ unsigned long long sched_clock(void)
return cycles_2_ns(a);
}
-/* Code to compensate for TSC C3 stalls */
+/* code to compensate for TSC C3 stalls: */
static u64 tsc_c3_offset;
static int tsc_unstable;
+
static inline int check_tsc_unstable(void)
{
return tsc_unstable;
@@ -266,6 +269,7 @@ static inline void mark_tsc_unstable(voi
void tsc_c3_compensate(unsigned long nsecs)
{
u64 cycles = ((u64)nsecs * tsc_khz)/1000000;
+
tsc_c3_offset += cycles;
}
@@ -334,7 +338,7 @@ unsigned long get_cmos_time(void)
return mktime(year, mon, day, hour, min, sec);
}
-/* arch specific timeofday hooks */
+/* arch specific timeofday hooks: */
u64 read_persistent_clock(void)
{
return (u64)get_cmos_time() * NSEC_PER_SEC;
@@ -1042,55 +1046,60 @@ static int __init notsc_setup(char *s)
__setup("notsc", notsc_setup);
-/* Clock source code */
-#include <linux/clocksource.h>
-#include <asm/vsyscall.h>
+/* clock-source code: */
static unsigned long current_tsc_khz = 0;
+
static int tsc_update_callback(void);
#ifdef CONFIG_PARANOID_GENERIC_TIME
/* This will hurt performance! */
-DEFINE_SPINLOCK(checktsc_lock);
-cycle_t last_tsc;
+static DEFINE_SPINLOCK(checktsc_lock);
+static cycle_t last_tsc;
static cycle_t read_tsc(void)
{
- cycle_t ret;
unsigned long flags;
+ cycle_t ret;
+
spin_lock_irqsave(&checktsc_lock, flags);
rdtscll(ret);
- if(ret < last_tsc)
+ if (ret < last_tsc)
printk("read_tsc: ACK! TSC went backward! Unsynced TSCs?\n");
last_tsc = ret;
spin_unlock_irqrestore(&checktsc_lock, flags);
+
return ret;
}
static cycle_t __vsyscall_fn vread_tsc(void* unused)
{
cycle_t ret;
+
rdtscll(ret);
+
return ret;
}
static cycle_t read_tsc_c3(void)
{
- cycle_t ret;
unsigned long flags;
+ cycle_t ret;
+
spin_lock_irqsave(&checktsc_lock, flags);
rdtscll(ret);
ret += tsc_read_c3_time();
- if(ret < last_tsc)
+ if (ret < last_tsc)
printk("read_tsc_c3: ACK! TSC went backward! Unsynced TSCs?\n");
last_tsc = ret;
spin_unlock_irqrestore(&checktsc_lock, flags);
+
return ret;
}
@@ -1099,43 +1108,37 @@ static cycle_t read_tsc_c3(void)
static cycle_t read_tsc(void)
{
cycle_t ret;
+
rdtscll(ret);
+
return ret;
}
static cycle_t __vsyscall_fn vread_tsc(void* unused)
{
cycle_t ret;
+
rdtscll(ret);
+
return ret;
}
static cycle_t read_tsc_c3(void)
{
cycle_t ret;
+
rdtscll(ret);
+
return ret + tsc_read_c3_time();
}
#endif /* CONFIG_PARANOID_GENERIC_TIME */
-static struct clocksource clocksource_tsc = {
- .name = "tsc",
- .rating = 300,
- .read = read_tsc,
- .vread = vread_tsc,
- .mask = (cycle_t)-1,
- .mult = 0, /* to be set */
- .shift = 22,
- .update_callback = tsc_update_callback,
- .is_continuous = 1,
-};
-
-
static int tsc_update_callback(void)
{
int change = 0;
- /* check to see if we should switch to the safe clocksource */
+
+ /* check to see if we should switch to the safe clocksource: */
if (tsc_read_c3_time() &&
strncmp(clocksource_tsc.name, "c3tsc", 5)) {
printk("Falling back to C3 safe TSC\n");
@@ -1150,7 +1153,8 @@ static int tsc_update_callback(void)
reselect_clocksource();
change = 1;
}
- /* only update if tsc_khz has changed */
+
+ /* only update if tsc_khz has changed: */
if (current_tsc_khz != tsc_khz){
current_tsc_khz = tsc_khz;
clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
@@ -1174,12 +1178,11 @@ static int __init init_tsc_clocksource(v
module_init(init_tsc_clocksource);
-#define HPET_MASK (0xFFFFFFFF)
-#define HPET_SHIFT 22
+#define HPET_MASK 0xFFFFFFFF
+#define HPET_SHIFT 22
/* FSEC = 10^-15 NSEC = 10^-9 */
-#define FSEC_PER_NSEC 1000000
-
+#define FSEC_PER_NSEC 1000000
static void *hpet_ptr;
@@ -1194,35 +1197,35 @@ static cycle_t __vsyscall_fn vread_hpet(
}
struct clocksource clocksource_hpet = {
- .name = "hpet",
- .rating = 250,
- .read = read_hpet,
- .vread = vread_hpet,
- .mask = (cycle_t)HPET_MASK,
- .mult = 0, /* set below */
- .shift = HPET_SHIFT,
- .is_continuous = 1,
+ .name = "hpet",
+ .rating = 250,
+ .read = read_hpet,
+ .vread = vread_hpet,
+ .mask = (cycle_t)HPET_MASK,
+ .mult = 0, /* set below */
+ .shift = HPET_SHIFT,
+ .is_continuous = 1,
};
static int __init init_hpet_clocksource(void)
{
unsigned long hpet_period;
- void __iomem* hpet_base;
+ void __iomem *hpet_base;
u64 tmp;
if (!hpet_address)
return -ENODEV;
- /* calculate the hpet address */
+ /* calculate the hpet address: */
hpet_base =
(void __iomem*)ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
hpet_ptr = hpet_base + HPET_COUNTER;
- /* calculate the frequency */
+ /* calculate the frequency: */
hpet_period = readl(hpet_base + HPET_PERIOD);
-
- /* hpet period is in femto seconds per cycle
+ /*
+ * hpet period is in femto seconds per cycle
* so we need to convert this to ns/cyc units
* aproximated by mult/2^shift
*
@@ -1237,6 +1240,8 @@ static int __init init_hpet_clocksource(
clocksource_hpet.mult = (u32)tmp;
register_clocksource(&clocksource_hpet);
+
return 0;
}
+
module_init(init_hpet_clocksource);
Index: linux/arch/x86_64/kernel/vsyscall.c
===================================================================
--- linux.orig/arch/x86_64/kernel/vsyscall.c
+++ linux/arch/x86_64/kernel/vsyscall.c
@@ -29,8 +29,10 @@
#include <linux/jiffies.h>
#include <linux/sysctl.h>
+
#include <asm/vsyscall.h>
#include <asm/pgtable.h>
+#include <asm/unistd.h>
#include <asm/page.h>
#include <asm/fixmap.h>
#include <asm/errno.h>
@@ -42,7 +44,6 @@
int __sysctl_vsyscall __section_sysctl_vsyscall = 1;
seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED;
-
struct vsyscall_gtod_data_t {
struct timeval wall_time_tv;
struct timezone sys_tz;
@@ -56,9 +57,6 @@ struct vsyscall_gtod_data_t __vsyscall_g
extern seqlock_t vsyscall_gtod_lock;
seqlock_t __vsyscall_gtod_lock __section_vsyscall_gtod_lock = SEQLOCK_UNLOCKED;
-
-#include <asm/unistd.h>
-
static force_inline void timeval_normalize(struct timeval * tv)
{
time_t __sec;
@@ -70,22 +68,28 @@ static force_inline void timeval_normali
}
}
-/* XXX - this is ugly. gettimeofday() has a label in it so we can't
- call it twice.
+/*
+ * XXX - this is ugly. gettimeofday() has a label in it so we can't
+ * call it twice.
*/
static force_inline int syscall_gtod(struct timeval *tv, struct timezone *tz)
{
int ret;
+
asm volatile("syscall"
: "=a" (ret)
- : "0" (__NR_gettimeofday),"D" (tv),"S" (tz) : __syscall_clobber );
+ : "0" (__NR_gettimeofday),"D" (tv),"S" (tz)
+ : __syscall_clobber);
+
return ret;
}
-static force_inline void do_vgettimeofday(struct timeval* tv)
+
+static force_inline void do_vgettimeofday(struct timeval *tv)
{
cycle_t now, cycle_delta;
nsec_t nsec_delta;
unsigned long seq;
+
do {
seq = read_seqbegin(&__vsyscall_gtod_lock);
@@ -109,6 +113,7 @@ static force_inline void do_vgettimeofda
*tv = __vsyscall_gtod_data.wall_time_tv;
do_div(nsec_delta, NSEC_PER_USEC);
tv->tv_usec += (unsigned long) nsec_delta;
+
while (tv->tv_usec > USEC_PER_SEC) {
tv->tv_sec += 1;
tv->tv_usec -= USEC_PER_SEC;
@@ -116,7 +121,10 @@ static force_inline void do_vgettimeofda
} while (read_seqretry(&__vsyscall_gtod_lock, seq));
}
-/* RED-PEN may want to readd seq locking, but then the variable should be write-once. */
+/*
+ * RED-PEN may want to readd seq locking, but then the variable should be
+ * write-once.
+ */
static force_inline void do_get_tz(struct timezone * tz)
{
*tz = __vsyscall_gtod_data.sys_tz;
@@ -156,11 +164,14 @@ int __vsyscall(0) vgettimeofday(struct t
time_t __vsyscall(1) vtime(time_t *t)
{
struct timeval tv;
+
if (unlikely(!__sysctl_vsyscall))
return time_syscall(t);
+
vgettimeofday(&tv, 0);
if (t)
*t = tv.tv_sec;
+
return tv.tv_sec;
}
@@ -174,7 +185,7 @@ long __vsyscall(3) venosys_1(void)
return -ENOSYS;
}
-struct clocksource* curr_clock;
+struct clocksource *curr_clock;
void arch_update_vsyscall_gtod(struct timespec wall_time, cycle_t offset_base,
struct clocksource *clock, int ntp_adj)
@@ -184,28 +195,26 @@ void arch_update_vsyscall_gtod(struct ti
write_seqlock_irqsave(&vsyscall_gtod_lock, flags);
/* XXX - hackitty hack hack. this is terrible! */
- if (curr_clock != clock) {
+ if (curr_clock != clock)
curr_clock = clock;
- }
- /* save off wall time as timeval */
+ /* save off wall time as timeval: */
vsyscall_gtod_data.wall_time_tv.tv_sec = wall_time.tv_sec;
vsyscall_gtod_data.wall_time_tv.tv_usec = wall_time.tv_nsec/1000;
- /* save offset_base */
+ /* save offset_base: */
vsyscall_gtod_data.offset_base = offset_base;
- /* copy current clocksource */
+ /* copy current clocksource: */
vsyscall_gtod_data.clock = *clock;
- /* apply ntp adjustment to clocksource mult */
+ /* apply ntp adjustment to clocksource mult: */
vsyscall_gtod_data.clock.mult += ntp_adj;
- /* save off current timezone */
+ /* save off current timezone: */
vsyscall_gtod_data.sys_tz = sys_tz;
write_sequnlock_irqrestore(&vsyscall_gtod_lock, flags);
-
}
#ifdef CONFIG_SYSCTL
-
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