From: Glauber Costa <glommer@redhat.com>
To: kvm@vger.kernel.org
Cc: avi@redhat.com, zamsden@redhat.com, mtosatti@redhat.com, riel@redhat.com
Subject: [RFC 1/7] Implement getnsboottime kernel API
Date: Wed, 25 Aug 2010 17:43:11 -0400 [thread overview]
Message-ID: <1282772597-4183-2-git-send-email-glommer@redhat.com> (raw)
In-Reply-To: <1282772597-4183-1-git-send-email-glommer@redhat.com>
From: Zachary Amsden <zamsden@redhat.com>
Add a kernel call to get the number of nanoseconds since boot. This
is generally useful enough to make it a generic call.
Signed-off-by: Zachary Amsden <zamsden@redhat.com>
---
include/linux/time.h | 1 +
kernel/time/timekeeping.c | 27 +++++++++++++++++++++++++++
2 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/include/linux/time.h b/include/linux/time.h
index ea3559f..5d04108 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -145,6 +145,7 @@ extern void getnstimeofday(struct timespec *tv);
extern void getrawmonotonic(struct timespec *ts);
extern void getboottime(struct timespec *ts);
extern void monotonic_to_bootbased(struct timespec *ts);
+extern s64 getnsboottime(void);
extern struct timespec timespec_trunc(struct timespec t, unsigned gran);
extern int timekeeping_valid_for_hres(void);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index caf8d4d..d250f0a 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -285,6 +285,33 @@ void ktime_get_ts(struct timespec *ts)
}
EXPORT_SYMBOL_GPL(ktime_get_ts);
+
+/**
+ * getnsboottime - get the bootbased clock in nsec format
+ *
+ * The function calculates the bootbased clock from the realtime
+ * clock and the wall_to_monotonic offset and stores the result
+ * in normalized timespec format in the variable pointed to by @ts.
+ */
+s64 getnsboottime(void)
+{
+ unsigned int seq;
+ s64 secs, nsecs;
+
+ WARN_ON(timekeeping_suspended);
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ secs = xtime.tv_sec + wall_to_monotonic.tv_sec;
+ secs += total_sleep_time.tv_sec;
+ nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;
+ nsecs += total_sleep_time.tv_nsec + timekeeping_get_ns();
+
+ } while (read_seqretry(&xtime_lock, seq));
+ return nsecs + (secs * NSEC_PER_SEC);
+}
+EXPORT_SYMBOL_GPL(getnsboottime);
+
/**
* do_gettimeofday - Returns the time of day in a timeval
* @tv: pointer to the timeval to be set
--
1.6.2.2
next prev parent reply other threads:[~2010-08-25 21:59 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-25 21:43 [RFC 0/7] KVM steal time implementation Glauber Costa
2010-08-25 21:43 ` Glauber Costa [this message]
2010-08-25 21:43 ` [RFC 2/7] change headers preparing for steal time Glauber Costa
2010-08-25 21:43 ` [RFC 3/7] measure time out of guest Glauber Costa
2010-08-25 21:43 ` [RFC 4/7] change kernel accounting to include steal time Glauber Costa
2010-08-25 21:43 ` [RFC 5/7] kvm steal time implementation Glauber Costa
2010-08-25 21:43 ` [RFC 6/7] touch softlockup watchdog Glauber Costa
2010-08-25 21:43 ` [RFC 7/7] tell guest about steal time feature Glauber Costa
2010-08-26 22:13 ` [RFC 5/7] kvm steal time implementation Rik van Riel
2010-08-26 22:35 ` Glauber Costa
2010-08-26 17:23 ` [RFC 4/7] change kernel accounting to include steal time Marcelo Tosatti
2010-08-26 20:28 ` Glauber Costa
2010-08-26 20:47 ` Marcelo Tosatti
2010-08-26 21:05 ` Rik van Riel
2010-08-26 21:13 ` Glauber Costa
2010-08-26 21:14 ` Anthony Liguori
2010-08-26 21:40 ` Glauber Costa
2010-08-26 23:12 ` Marcelo Tosatti
2010-08-27 0:33 ` Glauber Costa
2010-08-27 15:25 ` Marcelo Tosatti
2010-08-26 21:19 ` Rik van Riel
2010-08-26 21:39 ` Glauber Costa
2010-08-29 9:59 ` Avi Kivity
2010-08-29 15:13 ` Rik van Riel
2010-08-29 15:25 ` Avi Kivity
2010-08-29 15:42 ` Rik van Riel
2010-08-29 15:47 ` Avi Kivity
2010-08-30 12:42 ` Glauber Costa
2010-08-30 13:15 ` Avi Kivity
2010-08-26 20:54 ` [RFC 3/7] measure time out of guest Zachary Amsden
2010-08-26 21:14 ` Glauber Costa
2010-08-29 9:53 ` Avi Kivity
2010-08-26 20:44 ` [RFC 2/7] change headers preparing for steal time Zachary Amsden
2010-08-26 21:04 ` Rik van Riel
2010-08-26 21:17 ` Glauber Costa
2010-08-26 22:11 ` Rik van Riel
2010-08-29 9:51 ` Avi Kivity
2010-08-30 12:44 ` Glauber Costa
2010-08-30 13:10 ` Avi Kivity
2010-08-26 19:46 ` [RFC 1/7] Implement getnsboottime kernel API Rik van Riel
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