From: John Stultz <john.stultz@linaro.org>
To: lkml <linux-kernel@vger.kernel.org>
Cc: "Christopher S. Hall" <christopher.s.hall@intel.com>,
Prarit Bhargava <prarit@redhat.com>,
Richard Cochran <richardcochran@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
kevin.b.stanton@intel.com, kevin.j.clarke@intel.com,
hpa@zytor.com, jeffrey.t.kirsher@intel.com,
netdev@vger.kernel.org, John Stultz <john.stultz@linaro.org>
Subject: [PATCH 2/8] time: Add timekeeping snapshot code capturing system time and counter
Date: Wed, 2 Mar 2016 20:21:53 -0800 [thread overview]
Message-ID: <1456978919-30076-3-git-send-email-john.stultz@linaro.org> (raw)
In-Reply-To: <1456978919-30076-1-git-send-email-john.stultz@linaro.org>
From: "Christopher S. Hall" <christopher.s.hall@intel.com>
In the current timekeeping code there isn't any interface to
atomically capture the current relationship between the system counter
and system time. ktime_get_snapshot() returns this triple (counter,
monotonic raw, realtime) in the system_time_snapshot struct.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
[jstultz: Moved structure definitions around to clean things up,
fixed cycles_t/cycle_t confusion.]
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
include/linux/timekeeping.h | 18 ++++++++++++++++++
kernel/time/timekeeping.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 48 insertions(+)
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index ec89d84..7817591 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -267,6 +267,24 @@ extern void ktime_get_raw_and_real_ts64(struct timespec64 *ts_raw,
struct timespec64 *ts_real);
/*
+ * struct system_time_snapshot - simultaneous raw/real time capture with
+ * counter value
+ * @cycles: Clocksource counter value to produce the system times
+ * @real: Realtime system time
+ * @raw: Monotonic raw system time
+ */
+struct system_time_snapshot {
+ cycle_t cycles;
+ ktime_t real;
+ ktime_t raw;
+};
+
+/*
+ * Simultaneously snapshot realtime and monotonic raw clocks
+ */
+extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
+
+/*
* Persistent clock related interfaces
*/
extern int persistent_clock_is_local;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4243d28..89b4695 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -874,6 +874,36 @@ time64_t __ktime_get_real_seconds(void)
return tk->xtime_sec;
}
+/**
+ * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
+ * @systime_snapshot: pointer to struct receiving the system time snapshot
+ */
+void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+ unsigned long seq;
+ ktime_t base_raw;
+ ktime_t base_real;
+ s64 nsec_raw;
+ s64 nsec_real;
+ cycle_t now;
+
+ do {
+ seq = read_seqcount_begin(&tk_core.seq);
+
+ now = tk->tkr_mono.read(tk->tkr_mono.clock);
+ base_real = ktime_add(tk->tkr_mono.base,
+ tk_core.timekeeper.offs_real);
+ base_raw = tk->tkr_raw.base;
+ nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
+ nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
+ } while (read_seqcount_retry(&tk_core.seq, seq));
+
+ systime_snapshot->cycles = now;
+ systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
+ systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
+}
+EXPORT_SYMBOL_GPL(ktime_get_snapshot);
#ifdef CONFIG_NTP_PPS
--
1.9.1
next prev parent reply other threads:[~2016-03-03 4:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-03 4:21 [PATCH 0/8][GIT PULL] time: Cross-timestamp infrastructure for 4.6 John Stultz
2016-03-03 4:21 ` [PATCH 1/8] time: Add cycles to nanoseconds translation John Stultz
2016-03-03 4:21 ` John Stultz [this message]
2016-03-03 4:21 ` [PATCH 3/8] time: Remove duplicated code in ktime_get_raw_and_real() John Stultz
2016-03-03 4:21 ` [PATCH 4/8] time: Add driver cross timestamp interface for higher precision time synchronization John Stultz
2016-03-03 4:21 ` [PATCH 5/8] time: Add history to cross timestamp interface supporting slower devices John Stultz
2016-03-03 4:21 ` [PATCH 6/8] x86: tsc: Always Running Timer (ART) correlated clocksource John Stultz
2016-03-03 10:21 ` Thomas Gleixner
2016-03-03 22:24 ` John Stultz
2016-03-03 4:21 ` [PATCH 7/8] ptp: Add PTP_SYS_OFFSET_PRECISE for driver crosstimestamping John Stultz
2016-03-03 4:21 ` [PATCH 8/8] net: e1000e: Adds hardware supported cross timestamp on e1000e nic John Stultz
2016-03-03 22:27 ` Jeff Kirsher
2016-03-03 22:29 ` John Stultz
2016-03-04 1:56 [PATCHv2 0/8][GIT PULLv2] time: Cross-timestamp infrastructure for 4.6 John Stultz
2016-03-04 1:57 ` [PATCH 2/8] time: Add timekeeping snapshot code capturing system time and counter John Stultz
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