By popular demand, add a MONOTONIC_RAW variant.
The implementation is up for discussion; but given the need for the
dummy thing I thought it was easiest to just always update the
mono_raw clock state in timekeeping_update() for now, even though its
mostly wasted cycles.
I suppose the right place would be a resume callback somewhere.
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: John Stultz <john.stu...@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
include/linux/timekeeping.h | 1 +
kernel/time/timekeeping.c | 42 +++++++++++++++++++++++++++++++++++-------
2 files changed, 36 insertions(+), 7 deletions(-)
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -220,6 +220,7 @@ static inline u64 ktime_get_raw_ns(void)
}
extern u64 ktime_get_mono_fast_ns(void);
+extern u64 ktime_get_mono_raw_fast_ns(void);
/*
* Timespec interfaces utilizing the ktime based ones
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -58,7 +58,8 @@ struct tk_fast {
struct tk_read_base base[2];
};
-static struct tk_fast tk_fast_mono ____cacheline_aligned;
+static struct tk_fast tk_fast_mono ____cacheline_aligned;
+static struct tk_fast tk_fast_mono_raw ____cacheline_aligned;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
@@ -267,18 +268,18 @@ static inline s64 timekeeping_get_ns_raw
* slightly wrong timestamp (a few nanoseconds). See
* @ktime_get_mono_fast_ns.
*/
-static void update_fast_timekeeper(struct tk_read_base *tkr)
+static void update_fast_timekeeper(struct tk_fast *fast, struct tk_read_base
*tkr)
{
- struct tk_read_base *base = tk_fast_mono.base;
+ struct tk_read_base *base = fast->base;
/* Force readers off to base[1] */
- raw_write_seqcount_latch(&tk_fast_mono.seq);
+ raw_write_seqcount_latch(&fast->seq);
/* Update base[0] */
memcpy(base, tkr, sizeof(*base));
/* Force readers back to base[0] */
- raw_write_seqcount_latch(&tk_fast_mono.seq);
+ raw_write_seqcount_latch(&fast->seq);
/* Update base[1] */
memcpy(base + 1, base, sizeof(*base));
@@ -332,6 +333,22 @@ u64 notrace ktime_get_mono_fast_ns(void)
}
EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
+u64 notrace ktime_get_mono_raw_fast_ns(void)
+{
+ struct tk_read_base *tkr;
+ unsigned int seq;
+ u64 now;
+
+ do {
+ seq = raw_read_seqcount(&tk_fast_mono_raw.seq);
+ tkr = tk_fast_mono_raw.base + (seq & 0x01);
+ now = ktime_to_ns(tkr->base_mono) + timekeeping_get_ns(tkr);
+
+ } while (read_seqcount_retry(&tk_fast_mono_raw.seq, seq));
+ return now;
+}
+EXPORT_SYMBOL_GPL(ktime_get_mono_raw_fast_ns);
+
/* Suspend-time cycles value for halted fast timekeeper. */
static cycle_t cycles_at_suspend;
@@ -358,7 +375,11 @@ static void halt_fast_timekeeper(struct
memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
cycles_at_suspend = tkr->read(tkr->clock);
tkr_dummy.read = dummy_clock_read;
- update_fast_timekeeper(&tkr_dummy);
+ update_fast_timekeeper(&tk_fast_mono, &tkr_dummy);
+
+ tkr_dummy.mult = tkr->clock->mult;
+ tkr_dummy.shift = tkr->clock->shift;
+ update_fast_timekeeper(&tk_fast_mono_raw, &tkr_dummy);
}
#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
@@ -475,6 +496,8 @@ static inline void tk_update_ktime_data(
/* must hold timekeeper_lock */
static void timekeeping_update(struct timekeeper *tk, unsigned int action)
{
+ static struct tk_read_base tkr;
+
if (action & TK_CLEAR_NTP) {
tk->ntp_error = 0;
ntp_clear();
@@ -489,7 +512,12 @@ static void timekeeping_update(struct ti
memcpy(&shadow_timekeeper, &tk_core.timekeeper,
sizeof(tk_core.timekeeper));
- update_fast_timekeeper(&tk->tkr);
+ update_fast_timekeeper(&tk_fast_mono, &tk->tkr);
+
+ tkr = tk->tkr;
+ tkr.mult = tk->tkr.clock->mult;
+ tkr.shift = tk->tkr.clock->shift;
+ update_fast_timekeeper(&tk_fast_mono_raw, &tkr);
}
/**
--
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