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-rw-r--r--kernel/time/clocksource.c46
-rw-r--r--kernel/time/ntp.c3
-rw-r--r--kernel/time/sched_clock.c111
3 files changed, 94 insertions, 66 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 50a8736757f3..64cf63ca09cc 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -479,6 +479,7 @@ static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
static inline void clocksource_resume_watchdog(void) { }
static inline int __clocksource_watchdog_kthread(void) { return 0; }
static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }
+void clocksource_mark_unstable(struct clocksource *cs) { }
#endif /* CONFIG_CLOCKSOURCE_WATCHDOG */
@@ -537,40 +538,55 @@ static u32 clocksource_max_adjustment(struct clocksource *cs)
}
/**
- * clocksource_max_deferment - Returns max time the clocksource can be deferred
- * @cs: Pointer to clocksource
- *
+ * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted
+ * @mult: cycle to nanosecond multiplier
+ * @shift: cycle to nanosecond divisor (power of two)
+ * @maxadj: maximum adjustment value to mult (~11%)
+ * @mask: bitmask for two's complement subtraction of non 64 bit counters
*/
-static u64 clocksource_max_deferment(struct clocksource *cs)
+u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask)
{
u64 max_nsecs, max_cycles;
/*
* Calculate the maximum number of cycles that we can pass to the
* cyc2ns function without overflowing a 64-bit signed result. The
- * maximum number of cycles is equal to ULLONG_MAX/(cs->mult+cs->maxadj)
+ * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj)
* which is equivalent to the below.
- * max_cycles < (2^63)/(cs->mult + cs->maxadj)
- * max_cycles < 2^(log2((2^63)/(cs->mult + cs->maxadj)))
- * max_cycles < 2^(log2(2^63) - log2(cs->mult + cs->maxadj))
- * max_cycles < 2^(63 - log2(cs->mult + cs->maxadj))
- * max_cycles < 1 << (63 - log2(cs->mult + cs->maxadj))
+ * max_cycles < (2^63)/(mult + maxadj)
+ * max_cycles < 2^(log2((2^63)/(mult + maxadj)))
+ * max_cycles < 2^(log2(2^63) - log2(mult + maxadj))
+ * max_cycles < 2^(63 - log2(mult + maxadj))
+ * max_cycles < 1 << (63 - log2(mult + maxadj))
* Please note that we add 1 to the result of the log2 to account for
* any rounding errors, ensure the above inequality is satisfied and
* no overflow will occur.
*/
- max_cycles = 1ULL << (63 - (ilog2(cs->mult + cs->maxadj) + 1));
+ max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1));
/*
* The actual maximum number of cycles we can defer the clocksource is
- * determined by the minimum of max_cycles and cs->mask.
+ * determined by the minimum of max_cycles and mask.
* Note: Here we subtract the maxadj to make sure we don't sleep for
* too long if there's a large negative adjustment.
*/
- max_cycles = min_t(u64, max_cycles, (u64) cs->mask);
- max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult - cs->maxadj,
- cs->shift);
+ max_cycles = min(max_cycles, mask);
+ max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift);
+
+ return max_nsecs;
+}
+
+/**
+ * clocksource_max_deferment - Returns max time the clocksource can be deferred
+ * @cs: Pointer to clocksource
+ *
+ */
+static u64 clocksource_max_deferment(struct clocksource *cs)
+{
+ u64 max_nsecs;
+ max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj,
+ cs->mask);
/*
* To ensure that the clocksource does not wrap whilst we are idle,
* limit the time the clocksource can be deferred by 12.5%. Please
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index bb2215174f05..af8d1d4f3d55 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -475,6 +475,7 @@ static void sync_cmos_clock(struct work_struct *work)
* called as close as possible to 500 ms before the new second starts.
* This code is run on a timer. If the clock is set, that timer
* may not expire at the correct time. Thus, we adjust...
+ * We want the clock to be within a couple of ticks from the target.
*/
if (!ntp_synced()) {
/*
@@ -485,7 +486,7 @@ static void sync_cmos_clock(struct work_struct *work)
}
getnstimeofday(&now);
- if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) {
+ if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec * 5) {
struct timespec adjust = now;
fail = -ENODEV;
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 0b479a6a22bb..f388baeaf2b6 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -8,25 +8,28 @@
#include <linux/clocksource.h>
#include <linux/init.h>
#include <linux/jiffies.h>
+#include <linux/ktime.h>
#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/syscore_ops.h>
-#include <linux/timer.h>
+#include <linux/hrtimer.h>
#include <linux/sched_clock.h>
+#include <linux/seqlock.h>
+#include <linux/bitops.h>
struct clock_data {
+ ktime_t wrap_kt;
u64 epoch_ns;
- u32 epoch_cyc;
- u32 epoch_cyc_copy;
+ u64 epoch_cyc;
+ seqcount_t seq;
unsigned long rate;
u32 mult;
u32 shift;
bool suspended;
};
-static void sched_clock_poll(unsigned long wrap_ticks);
-static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0);
+static struct hrtimer sched_clock_timer;
static int irqtime = -1;
core_param(irqtime, irqtime, int, 0400);
@@ -35,14 +38,25 @@ static struct clock_data cd = {
.mult = NSEC_PER_SEC / HZ,
};
-static u32 __read_mostly sched_clock_mask = 0xffffffff;
+static u64 __read_mostly sched_clock_mask;
-static u32 notrace jiffy_sched_clock_read(void)
+static u64 notrace jiffy_sched_clock_read(void)
{
- return (u32)(jiffies - INITIAL_JIFFIES);
+ /*
+ * We don't need to use get_jiffies_64 on 32-bit arches here
+ * because we register with BITS_PER_LONG
+ */
+ return (u64)(jiffies - INITIAL_JIFFIES);
}
-static u32 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read;
+static u32 __read_mostly (*read_sched_clock_32)(void);
+
+static u64 notrace read_sched_clock_32_wrapper(void)
+{
+ return read_sched_clock_32();
+}
+
+static u64 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read;
static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
{
@@ -52,25 +66,18 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
static unsigned long long notrace sched_clock_32(void)
{
u64 epoch_ns;
- u32 epoch_cyc;
- u32 cyc;
+ u64 epoch_cyc;
+ u64 cyc;
+ unsigned long seq;
if (cd.suspended)
return cd.epoch_ns;
- /*
- * Load the epoch_cyc and epoch_ns atomically. We do this by
- * ensuring that we always write epoch_cyc, epoch_ns and
- * epoch_cyc_copy in strict order, and read them in strict order.
- * If epoch_cyc and epoch_cyc_copy are not equal, then we're in
- * the middle of an update, and we should repeat the load.
- */
do {
+ seq = read_seqcount_begin(&cd.seq);
epoch_cyc = cd.epoch_cyc;
- smp_rmb();
epoch_ns = cd.epoch_ns;
- smp_rmb();
- } while (epoch_cyc != cd.epoch_cyc_copy);
+ } while (read_seqcount_retry(&cd.seq, seq));
cyc = read_sched_clock();
cyc = (cyc - epoch_cyc) & sched_clock_mask;
@@ -83,49 +90,46 @@ static unsigned long long notrace sched_clock_32(void)
static void notrace update_sched_clock(void)
{
unsigned long flags;
- u32 cyc;
+ u64 cyc;
u64 ns;
cyc = read_sched_clock();
ns = cd.epoch_ns +
cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask,
cd.mult, cd.shift);
- /*
- * Write epoch_cyc and epoch_ns in a way that the update is
- * detectable in cyc_to_fixed_sched_clock().
- */
+
raw_local_irq_save(flags);
- cd.epoch_cyc_copy = cyc;
- smp_wmb();
+ write_seqcount_begin(&cd.seq);
cd.epoch_ns = ns;
- smp_wmb();
cd.epoch_cyc = cyc;
+ write_seqcount_end(&cd.seq);
raw_local_irq_restore(flags);
}
-static void sched_clock_poll(unsigned long wrap_ticks)
+static enum hrtimer_restart sched_clock_poll(struct hrtimer *hrt)
{
- mod_timer(&sched_clock_timer, round_jiffies(jiffies + wrap_ticks));
update_sched_clock();
+ hrtimer_forward_now(hrt, cd.wrap_kt);
+ return HRTIMER_RESTART;
}
-void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
+void __init sched_clock_register(u64 (*read)(void), int bits,
+ unsigned long rate)
{
- unsigned long r, w;
+ unsigned long r;
u64 res, wrap;
char r_unit;
if (cd.rate > rate)
return;
- BUG_ON(bits > 32);
WARN_ON(!irqs_disabled());
read_sched_clock = read;
- sched_clock_mask = (1ULL << bits) - 1;
+ sched_clock_mask = CLOCKSOURCE_MASK(bits);
cd.rate = rate;
/* calculate the mult/shift to convert counter ticks to ns. */
- clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0);
+ clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 3600);
r = rate;
if (r >= 4000000) {
@@ -138,20 +142,14 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
r_unit = ' ';
/* calculate how many ns until we wrap */
- wrap = cyc_to_ns((1ULL << bits) - 1, cd.mult, cd.shift);
- do_div(wrap, NSEC_PER_MSEC);
- w = wrap;
+ wrap = clocks_calc_max_nsecs(cd.mult, cd.shift, 0, sched_clock_mask);
+ cd.wrap_kt = ns_to_ktime(wrap - (wrap >> 3));
/* calculate the ns resolution of this counter */
res = cyc_to_ns(1ULL, cd.mult, cd.shift);
- pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lums\n",
- bits, r, r_unit, res, w);
+ pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lluns\n",
+ bits, r, r_unit, res, wrap);
- /*
- * Start the timer to keep sched_clock() properly updated and
- * sets the initial epoch.
- */
- sched_clock_timer.data = msecs_to_jiffies(w - (w / 10));
update_sched_clock();
/*
@@ -166,6 +164,12 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
pr_debug("Registered %pF as sched_clock source\n", read);
}
+void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
+{
+ read_sched_clock_32 = read;
+ sched_clock_register(read_sched_clock_32_wrapper, bits, rate);
+}
+
unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32;
unsigned long long notrace sched_clock(void)
@@ -180,14 +184,22 @@ void __init sched_clock_postinit(void)
* make it the final one one.
*/
if (read_sched_clock == jiffy_sched_clock_read)
- setup_sched_clock(jiffy_sched_clock_read, 32, HZ);
+ sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ);
- sched_clock_poll(sched_clock_timer.data);
+ update_sched_clock();
+
+ /*
+ * Start the timer to keep sched_clock() properly updated and
+ * sets the initial epoch.
+ */
+ hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ sched_clock_timer.function = sched_clock_poll;
+ hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
}
static int sched_clock_suspend(void)
{
- sched_clock_poll(sched_clock_timer.data);
+ sched_clock_poll(&sched_clock_timer);
cd.suspended = true;
return 0;
}
@@ -195,7 +207,6 @@ static int sched_clock_suspend(void)
static void sched_clock_resume(void)
{
cd.epoch_cyc = read_sched_clock();
- cd.epoch_cyc_copy = cd.epoch_cyc;
cd.suspended = false;
}
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-05 05:15:28 +0000