From: David Vrabel <david.vrabel@citrix.com>
To: <xen-devel@lists.xen.org>
Cc: David Vrabel <david.vrabel@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
<linux-kernel@vger.kernel.org>,
John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 1/4] hrtimers: provide a hrtimers_late_resume() call
Date: Thu, 20 Jun 2013 20:16:29 +0100 [thread overview]
Message-ID: <1371755792-25962-2-git-send-email-david.vrabel@citrix.com> (raw)
In-Reply-To: <1371755792-25962-1-git-send-email-david.vrabel@citrix.com>
From: David Vrabel <david.vrabel@citrix.com>
Xen suspends (and resumes) without disabling non-boot CPUs as doing so
adds considerable delay to live migrations. A 4 VCPU guest had more
than 200 ms of additional downtime if disable_nonboot_cpus() was
called prior to suspending.
As a consequence, only high resolution timers on the current CPU are
retriggered when resuming. The Xen resume path worked around this
with a call to clock_was_set() to retrigger timers on all the CPUs.
A subsequent change will make clock_was_set() internal to hrtimers so
add an new call (hrtimers_late_resume()) to do the same job.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
drivers/xen/manage.c | 8 ++++++--
include/linux/hrtimer.h | 1 +
kernel/hrtimer.c | 9 +++++++++
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 412b96c..75bc2d5 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -166,8 +166,12 @@ out_resume:
dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
- /* Make sure timer events get retriggered on all CPUs */
- clock_was_set();
+ /*
+ * syscore_resume() ends up calling hrtimer_resume() but this
+ * only retriggers timer events on the current CPU. We need
+ * to retrigger the events on all the other CPUS.
+ */
+ hrtimers_late_resume();
out_thaw:
#ifdef CONFIG_PREEMPT
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index d19a5c2..13df0fa 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -323,6 +323,7 @@ extern void timerfd_clock_was_set(void);
static inline void timerfd_clock_was_set(void) { }
#endif
extern void hrtimers_resume(void);
+extern void hrtimers_late_resume(void);
extern ktime_t ktime_get(void);
extern ktime_t ktime_get_real(void);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index fd4b13b..34384b4 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -784,6 +784,15 @@ void hrtimers_resume(void)
timerfd_clock_was_set();
}
+/*
+ * If non-boot CPUs were online during resume, we need to retrigger
+ * the events for all the non-boot CPUs.
+ */
+void hrtimers_late_resume(void)
+{
+ clock_was_set();
+}
+
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
--
1.7.2.5
next prev parent reply other threads:[~2013-06-20 19:17 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 19:16 [PATCHv5 0/4] xen: maintain an accurate persistent clock in more cases David Vrabel
2013-06-20 19:16 ` David Vrabel [this message]
2013-06-21 7:53 ` [PATCH 1/4] hrtimers: provide a hrtimers_late_resume() call Thomas Gleixner
2013-06-21 12:32 ` David Vrabel
2013-06-21 14:32 ` Thomas Gleixner
2013-06-21 17:30 ` David Vrabel
2013-06-21 21:24 ` Thomas Gleixner
2013-06-20 19:16 ` [PATCH 2/4] time: add a notifier chain for when the system time is stepped David Vrabel
2013-06-21 7:57 ` Thomas Gleixner
2013-06-21 12:41 ` David Vrabel
2013-06-21 23:06 ` Thomas Gleixner
2013-06-24 10:51 ` David Vrabel
2013-06-24 16:30 ` Thomas Gleixner
2013-06-24 17:00 ` David Vrabel
2013-06-24 17:50 ` John Stultz
2013-06-24 19:55 ` Thomas Gleixner
2013-06-21 16:22 ` John Stultz
2013-06-20 19:16 ` [PATCH 3/4] x86/xen: sync the wallclock " David Vrabel
2013-06-20 19:16 ` [PATCH 4/4] x86/xen: sync the CMOS RTC as well as the Xen wallclock David Vrabel
2013-06-20 20:03 ` [PATCHv5 0/4] xen: maintain an accurate persistent clock in more cases John Stultz
2013-06-21 18:31 ` Konrad Rzeszutek Wilk
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