linux/kernel/time
Thomas Gleixner 41d2e49493 hrtimer: Tune hrtimer_interrupt hang logic
The hrtimer_interrupt hang logic adjusts min_delta_ns based on the
execution time of the hrtimer callbacks.

This is error-prone for virtual machines, where a guest vcpu can be
scheduled out during the execution of the callbacks (and the callbacks
themselves can do operations that translate to blocking operations in
the hypervisor), which in can lead to large min_delta_ns rendering the
system unusable.

Replace the current heuristics with something more reliable. Allow the
interrupt code to try 3 times to catch up with the lost time. If that
fails use the total time spent in the interrupt handler to defer the
next timer interrupt so the system can catch up with other things
which got delayed. Limit that deferment to 100ms.

The retry events and the maximum time spent in the interrupt handler
are recorded and exposed via /proc/timer_list

Inspired by a patch from Marcelo.

Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org
2009-12-10 13:08:11 +01:00
..
clockevents.c clockevents: Add missing include to pacify sparse 2009-11-18 12:31:48 +01:00
clocksource.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
jiffies.c clocksource: Cleanup clocksource selection 2009-08-15 10:55:46 +02:00
Kconfig Kconfig: eliminate "def_bool n" constructs 2008-10-16 11:21:31 -07:00
Makefile time: add function to convert between calendar time and broken-down time for universal use 2009-09-24 07:20:56 -07:00
ntp.c timekeeping: Introduce timekeeping_leap_insert 2009-08-15 10:55:45 +02:00
tick-broadcast.c clockevent: Prevent dead lock on clockevents_lock 2009-08-19 18:15:10 +02:00
tick-common.c clockevents: prevent endless loop in tick_handle_periodic() 2009-05-02 10:22:27 +02:00
tick-internal.h NOHZ: restart tick device from irq_enter() 2008-10-17 18:13:38 +02:00
tick-oneshot.c nohz: Allow 32-bit machines to sleep for more than 2.15 seconds 2009-11-13 20:46:24 +01:00
tick-sched.c Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 19:27:08 -08:00
timecompare.c clocksource/timecompare: Fix symbol exports to be GPL'd. 2009-11-11 19:06:30 -08:00
timeconv.c time: add function to convert between calendar time and broken-down time for universal use 2009-09-24 07:20:56 -07:00
timekeeping.c Merge branch 'timers-for-linus-urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 19:28:09 -08:00
timer_list.c hrtimer: Tune hrtimer_interrupt hang logic 2009-12-10 13:08:11 +01:00
timer_stats.c const: constify remaining file_operations 2009-10-01 16:11:11 -07:00