linux-toradex.git/kernel/time, branch v2.6.32.15

hrtimer: Tune hrtimer_interrupt hang logic

2010-04-01T22:58:14+00:00

commit 41d2e494937715d3150e5c75d01f0e75ae899337 upstream.

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 
Signed-off-by: Thomas Gleixner 
Tested-by: Marcelo Tosatti 
Cc: kvm@vger.kernel.org
Cc: Jeremy Fitzhardinge 
Signed-off-by: Greg Kroah-Hartman

timekeeping: Prevent oops when GENERIC_TIME=n

2010-04-01T22:58:06+00:00

commit ad6759fbf35d104dbf573cd6f4c6784ad6823f7e upstream.

Aaro Koskinen reported an issue in kernel.org bugzilla #15366, where
on non-GENERIC_TIME systems, accessing
/sys/devices/system/clocksource/clocksource0/current_clocksource
results in an oops.

It seems the timekeeper/clocksource rework missed initializing the
curr_clocksource value in the !GENERIC_TIME case.

Thanks to Aaro for reporting and diagnosing the issue as well as
testing the fix!

Reported-by: Aaro Koskinen 
Signed-off-by: John Stultz 
Cc: Martin Schwidefsky 
LKML-Reference: <1267475683.4216.61.camel@localhost.localdomain>
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

Export the symbol of getboottime and mmonotonic_to_bootbased

2010-02-23T15:37:52+00:00

commit c93d89f3dbf0202bf19c07960ca8602b48c2f9a0 upstream.

Export getboottime and monotonic_to_bootbased in order to let them
could be used by following patch.

Signed-off-by: Jason Wang 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Greg Kroah-Hartman

clocksource: fix compilation if no GENERIC_TIME

2010-02-09T12:50:54+00:00

commit a362c638bdf052bf424bce7645d39b101090f6ba upstream

Commit a9238ce3bb0fda6e760780b702c6cbd3793087d3 broke compilation on
platforms that do not implement GENERIC_TIME (e.g. iop32x):

  kernel/time/clocksource.c: In function 'clocksource_register':
  kernel/time/clocksource.c:556: error: implicit declaration of function 'clocksource_max_deferment'

Provide the implementation of clocksource_max_deferment() also for
such platforms.

Signed-off-by: Aaro Koskinen 
Cc: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

nohz: Prevent clocksource wrapping during idle

2010-01-28T23:01:12+00:00

commit 98962465ed9e6ea99c38e0af63fe1dcb5a79dc25 upstream.

The dynamic tick allows the kernel to sleep for periods longer than a
single tick, but it does not limit the sleep time currently. In the
worst case the kernel could sleep longer than the wrap around time of
the time keeping clock source which would result in losing track of
time.

Prevent this by limiting it to the safe maximum sleep time of the
current time keeping clock source. The value is calculated when the
clock source is registered.

[ tglx: simplified the code a bit and massaged the commit msg ]

Signed-off-by: Jon Hunter 
Cc: John Stultz 
LKML-Reference: <1250617512-23567-2-git-send-email-jon-hunter@ti.com>
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

clockevents: Add missing include to pacify sparse

2010-01-28T23:00:24+00:00

commit 8e1a928a2ed7e8d5cad97c8e985294b4caedd168 upstream.

Include "tick-internal.h" in order to pick up the extern function
prototype for clockevents_shutdown(). This quiets the following sparse
build noise:

  warning: symbol 'clockevents_shutdown' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten 
LKML-Reference: 
Reviewed-by: Yong Zhang 
Cc: johnstul@us.ibm.com
Signed-off-by: Andrew Morton 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

clockevent: Don't remove broadcast device when cpu is dead

2010-01-28T23:00:22+00:00

commit ea9d8e3f45404d411c00ae67b45cc35c58265bb7 upstream.

Marc reported that the BUG_ON in clockevents_notify() triggers on his
system. This happens because the kernel tries to remove an active
clock event device (used for broadcasting) from the device list.

The handling of devices which can be used as per cpu device and as a
global broadcast device is suboptimal.

The simplest solution for now (and for stable) is to check whether the
device is used as global broadcast device, but this needs to be
revisited.

[ tglx: restored the cpuweight check and massaged the changelog ]

Reported-by: Marc Dionne 
Tested-by: Marc Dionne 
Signed-off-by: Xiaotian Feng 
LKML-Reference: <1262834564-13033-1-git-send-email-dfeng@redhat.com>
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

clockevents: Prevent clockevent_devices list corruption on cpu hotplug

2010-01-06T23:03:21+00:00

commit bb6eddf7676e1c1f3e637aa93c5224488d99036f upstream.

Xiaotian Feng triggered a list corruption in the clock events list on
CPU hotplug and debugged the root cause.

If a CPU registers more than one per cpu clock event device, then only
the active clock event device is removed on CPU_DEAD. The unused
devices are kept in the clock events device list.

On CPU up the clock event devices are registered again, which means
that we list_add an already enqueued list_head. That results in list
corruption.

Resolve this by removing all devices which are associated to the dead
CPU on CPU_DEAD.

Reported-by: Xiaotian Feng 
Signed-off-by: Thomas Gleixner 
Tested-by: Xiaotian Feng 
Signed-off-by: Greg Kroah-Hartman

headers: remove sched.h from interrupt.h

2009-10-11T18:20:58+00:00

After m68k's task_thread_info() doesn't refer to current,
it's possible to remove sched.h from interrupt.h and not break m68k!
Many thanks to Heiko Carstens for allowing this.

Signed-off-by: Alexey Dobriyan

NOHZ: update idle state also when NOHZ is inactive

2009-10-07T11:05:05+00:00

Commit f2e21c9610991e95621a81407cdbab881226419b had unfortunate side
effects with cpufreq governors on some systems.

If the system did not switch into NOHZ mode ts->inidle is not set when
tick_nohz_stop_sched_tick() is called from the idle routine. Therefor
all subsequent calls from irq_exit() to tick_nohz_stop_sched_tick()
fail to call tick_nohz_start_idle(). This results in bogus idle
accounting information which is passed to cpufreq governors.

Set the inidle flag unconditionally of the NOHZ active state to keep
the idle time accounting correct in any case.

[ tglx: Added comment and tweaked the changelog ]

Reported-by: Steven Noonan 
Signed-off-by: Eero Nurkkala 
Cc: Rik van Riel 
Cc: Venkatesh Pallipadi 
Cc: Greg KH 
Cc: Steven Noonan 
Cc: stable@kernel.org
LKML-Reference: <1254907901.30157.93.camel@eenurkka-desktop>
Signed-off-by: Thomas Gleixner