Commit Graph

89 Commits

Author SHA1 Message Date
Ingo Molnar
f20bf61256 time: introduce xtime_seconds
improve performance of sys_time(). sys_time() returns time in seconds,
but it does so by calling do_gettimeofday() and then returning the
tv_sec portion of the GTOD time. But the data structure "xtime", which
is updated by every timer/scheduler tick, already offers HZ granularity
time.

the patch improves the sysbench oltp macrobenchmark by 4-5% on an AMD
dual-core system:

v2.6.23:

#threads

   1:     transactions:                        4073   (407.23 per sec.)
   2:     transactions:                        8530   (852.81 per sec.)
   3:     transactions:                        8321   (831.88 per sec.)
   4:     transactions:                        8407   (840.58 per sec.)
   5:     transactions:                        8070   (806.74 per sec.)

v2.6.23 + sys_time-speedup.patch:

   1:     transactions:                        4281   (428.09 per sec.)
   2:     transactions:                        8910   (890.85 per sec.)
   3:     transactions:                        8659   (865.79 per sec.)
   4:     transactions:                        8676   (867.34 per sec.)
   5:     transactions:                        8532   (852.91 per sec.)

and by 4-5% on an Intel dual-core system too:

2.6.23:

  1:     transactions:                        4560   (455.94 per sec.)
  2:     transactions:                        10094  (1009.30 per sec.)
  3:     transactions:                        9755   (975.36 per sec.)
  4:     transactions:                        9859   (985.78 per sec.)
  5:     transactions:                        9701   (969.72 per sec.)

2.6.23 + sys_time-speedup.patch:

  1:     transactions:                        4779   (477.84 per sec.)
  2:     transactions:                        10103  (1010.14 per sec.)
  3:     transactions:                        10141  (1013.93 per sec.)
  4:     transactions:                        10371  (1036.89 per sec.)
  5:     transactions:                        10178  (1017.50 per sec.)

(the more CPUs the system has, the more speedup this patch gives for
this particular workload.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 10:01:50 -07:00
Thomas Gleixner
1595f452f3 clockevents: introduce force broadcast notifier
The 64bit SMP bootup is slightly different to the 32bit one. It enables
the boot CPU local APIC timer before all CPUs are brought up. Some AMD C1E
systems have the C1E feature flag only set in the secondary CPU. Due to
the early enable of the boot CPU local APIC timer the APIC timer is
registered as a fully functional device. When we detect the wreckage during
the bringup of the secondary CPU, we need to force the boot CPU into
broadcast mode. 

Add a new notifier reason and implement the force broadcast in the clock
events layer.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-14 22:57:45 +02:00
Venki Pallipadi
4a93232dab clock events: allow replacement of broadcast timer
Change the broadcast timer, if a timer with higher rating becomes available.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-12 23:04:23 +02:00
Thomas Gleixner
c8a1d398de clockevents: fix periodic broadcast for oneshot devices
The next_event member of the clock event device is used to keep track
of the next periodic event. For one shot only devices it is wrong to
clear the variable, as the next event will be based on it.

Pointed out by Ralf Baechle

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2007-10-12 23:04:06 +02:00
Thomas Gleixner
de68d9b173 clockevents: Allow build w/o run-tine usage for migration purposes
Migration aid to allow preparatory patches which introduce not yet
used parts of clock events code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2007-10-12 23:04:05 +02:00
Anton Blanchard
74922be148 Fix timer_stats printout of events/sec
When using /proc/timer_stats on ppc64 I noticed the events/sec field wasnt
accurate.  Sometimes the integer part was incorrect due to rounding (we
werent taking the fractional seconds into consideration).

The fraction part is also wrong, we need to pad the printf statement and
take the bottom three digits of 1000 times the value.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-07 16:28:43 -07:00
Thomas Gleixner
b7e113dc9d clockevents: remove the suspend/resume workaround^Wthinko
In a desparate attempt to fix the suspend/resume problem on Andrews
VAIO I added a workaround which enforced the broadcast of the oneshot
timer on resume. This was actually resolving the problem on the VAIO
but was just a stupid workaround, which was not tackling the root
cause: the assignement of lower idle C-States in the ACPI processor_idle
code. The cpuidle patches, which utilize the dynamic tick feature and
go faster into deeper C-states exposed the problem again. The correct
solution is the previous patch, which prevents lower C-states across
the suspend/resume.

Remove the enforcement code, including the conditional broadcast timer
arming, which helped to pamper over the real problem for quite a time.
The oneshot broadcast flag for the cpu, which runs the resume code can
never be set at the time when this code is executed. It only gets set,
when the CPU is entering a lower idle C-State.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-22 17:15:34 -07:00
Thomas Gleixner
5e41d0d60a clockevents: prevent stale tick update on offline cpu
Taking a cpu offline removes the cpu from the online mask before the
CPU_DEAD notification is done. The clock events layer does the cleanup
of the dead CPU from the CPU_DEAD notifier chain. tick_do_timer_cpu is
used to avoid xtime lock contention by assigning the task of jiffies
xtime updates to one CPU. If a CPU is taken offline, then this
assignment becomes stale. This went unnoticed because most of the time
the offline CPU went dead before the online CPU reached __cpu_die(),
where the CPU_DEAD state is checked. In the case that the offline CPU did
not reach the DEAD state before we reach __cpu_die(), the code in there
goes to sleep for 100ms. Due to the stale time update assignment, the
system is stuck forever.

Take the assignment away when a cpu is not longer in the cpu_online_mask.
We do this in the last call to tick_nohz_stop_sched_tick() when the offline
CPU is on the way to the final play_dead() idle entry.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-09-16 15:36:43 +02:00
Thomas Gleixner
31d9b3938c clockevents: do not shutdown the oneshot broadcast device
When a cpu goes offline it is removed from the broadcast masks. If the
mask becomes empty the code shuts down the broadcast device. This is
wrong, because the broadcast device needs to be ready for the online
cpu going idle (into a c-state, which stops the local apic timer).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-09-16 15:36:43 +02:00
Thomas Gleixner
07eec6af44 clockevents: Enforce oneshot broadcast when broadcast mask is set on resume
The jinxed VAIO refuses to resume without hitting keys on the keyboard
when this is not enforced. It is unclear why the cpu ends up in a lower
C State without notifying the clock events layer, but enforcing the
oneshot broadcast here is safe.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-09-16 15:36:43 +02:00
Thomas Gleixner
6a669ee8a7 timekeeping: Prevent time going backwards on resume
Timekeeping resume adjusts xtime by adding the slept time in seconds and
resets the reference value of the clock source (clock->cycle_last).
clock->cycle last is used to calculate the delta between the last xtime
update and the readout of the clock source in __get_nsec_offset(). xtime
plus the offset is the current time. The resume code ignores the delta
which had already elapsed between the last xtime update and the actual
time of suspend. If the suspend time is short, then we can see time
going backwards on resume.

Suspend:
offs_s = clock->read() - clock->cycle_last;
now = xtime + offs_s;
timekeeping_suspend_time = read_rtc();

Resume:
sleep_time = read_rtc() - timekeeping_suspend_time;
xtime.tv_sec += sleep_time;
clock->cycle_last = clock->read();
offs_r = clock->read() - clock->cycle_last;
now = xtime + offs_r;

if sleep_time_seconds == 0 and offs_r < offs_s, then time goes
backwards.

Fix this by storing the offset from the last xtime update and add it to
xtime during resume, when we reset clock->cycle_last:

sleep_time = read_rtc() - timekeeping_suspend_time;
xtime.tv_sec += sleep_time;
xtime += offs_s;	/* Fixup xtime offset at suspend time */
clock->cycle_last = clock->read();
offs_r = clock->read() - clock->cycle_last;
now = xtime + offs_r;

Thanks to Marcelo for tracking this down on the OLPC and providing the
necessary details to analyze the root cause.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Tosatti <marcelo@kvack.org>
2007-09-16 15:36:43 +02:00
Thomas Gleixner
3be9095063 timekeeping: access rtc outside of xtime lock
Lockdep complains about the access of rtc in timekeeping_suspend
inside the interrupt disabled region of the write locked xtime lock.
Move the access outside.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@us.ibm.com>
2007-09-16 15:36:43 +02:00
Tony Breeds
298a5df45d Fix "no_sync_cmos_clock" logic inversion in kernel/time/ntp.c
Seems to me that this timer will only get started on platforms that say
they don't want it?

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gabriel Paubert <paubert@iram.es>
Cc: Zachary Amsden <zach@vmware.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-11 17:21:27 -07:00
Miao Xie
6ddfca9548 timer: remove clockevents_unregister_notifier
I find a function(clockevents_unregister_notifier) which is not called by
anything in tree.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-08-11 15:47:42 -07:00
Alexey Dobriyan
5ea473a1df Fix leaks on /proc/{*/sched,sched_debug,timer_list,timer_stats}
On every open/close one struct seq_operations leaks.
Kudos to /proc/slab_allocators.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-31 15:39:40 -07:00
john stultz
17c38b7490 Cache xtime every call to update_wall_time
This avoids xtime lag seen with dynticks, because while 'xtime' itself
is still not updated often, we keep a 'xtime_cache' variable around that
contains the approximate real-time that _is_ updated each time we do a
'update_wall_time()', and is thus never off by more than one tick.

IOW, this restores the original semantics for 'xtime' users, as long as
you use the proper abstraction functions (ie 'current_kernel_time()' or
'get_seconds()' depending on whether you want a timespec or just the
seconds field).

[ Updated Patch.  As penance for my sins I've also yanked another #ifdef
  that was added to avoid the xtime lag w/ hrtimers.  ]

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-25 10:17:44 -07:00
john stultz
2c6b47de17 Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time().
This avoids use of the kernel-internal "xtime" variable directly outside
of the actual time-related functions.  Instead, use the helper functions
that we already have available to us.

This doesn't actually change any behaviour, but this will allow us to
fix the fact that "xtime" isn't updated very often with CONFIG_NO_HZ
(because much of the realtime information is maintained as separate
offsets to 'xtime'), which has caused interfaces that use xtime directly
to get a time that is out of sync with the real-time clock by up to a
third of a second or so.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-25 10:09:20 -07:00
Thomas Gleixner
82644459c5 NTP: move the cmos update code into ntp.c
i386 and sparc64 have the identical code to update the cmos clock.  Move it
into kernel/time/ntp.c as there are other architectures coming along with the
same requirements.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 17:49:15 -07:00
Ingo Molnar
820de5c39e highres: improve debug output
Add some more debug information to the hrtimer and clock events code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 17:49:15 -07:00
john stultz
3704540b48 tick management: spread timer interrupt
After discussing w/ Thomas over IRC, it seems the issue is the sched tick
fires on every cpu at the same time, causing extra lock contention.

This smaller change, adds an extra offset per cpu so the ticks don't line up.
This patch also drops the idle latency from 40us down to under 20us.

Signed-off-by: john stultz <johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 17:49:15 -07:00
Thomas Gleixner
5590a536c0 clockevents: fix device replacement
When a device is replaced by a better rated device, then the broadcast
mode needs to be evaluated again. When the new device has no requirement
for broadcasting, then the broadcast bits for the CPU must be cleared.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 17:49:15 -07:00
Thomas Gleixner
18de5bc4c1 clockevents: fix resume logic
We need to make sure, that the clockevent devices are resumed, before
the tick is resumed. The current resume logic does not guarantee this.

Add CLOCK_EVT_MODE_RESUME and call the set mode functions of the clock
event devices before resuming the tick / oneshot functionality.

Fixup the existing users.

Thanks to Nigel Cunningham for tracking down a long standing thinko,
which affected the jinxed VAIO.

[akpm@linux-foundation.org: xen build fix]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 17:49:15 -07:00
Tony Luck
c36c282b88 Pull ia64-clocksource into release branch 2007-07-20 11:26:47 -07:00
Bob Picco
1f564ad6d4 [IA64] remove time interpolator
Remove time_interpolator code (This is generic code, but
only user was ia64.  It has been superseded by the
CONFIG_GENERIC_TIME code).

Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Peter Keilty <peter.keilty@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2007-07-20 11:23:02 -07:00
Thomas Gleixner
71120f183b timekeeping: fixup shadow variable argument
clocksource_adjust() has a clock argument, which shadows the file global clock
variable.  Fix this up.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:52 -07:00
Tejun Heo
9281acea6a kallsyms: make KSYM_NAME_LEN include space for trailing '\0'
KSYM_NAME_LEN is peculiar in that it does not include the space for the
trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
buffer.  This is nonsense and error-prone.  Moreover, when the caller
forgets that it's very likely to subtly bite back by corrupting the stack
because the last position of the buffer is always cleared to zero.

This patch increments KSYM_NAME_LEN by one and updates code accordingly.

* off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
  is fixed.

* Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
  MODULE_NAME_LEN was treated as if it didn't include space for the
  trailing '\0'.  Fix it.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:03 -07:00
Alexey Dobriyan
aa0ac36518 Remove capability.h from mm.h
I forgot to remove capability.h from mm.h while removing sched.h!  This
patch remedies that, because the only inline function which was using
CAP_something was made out of line.

Cross-compile tested without regressions on:

	all powerpc defconfigs
	all mips defconfigs
	all m68k defconfigs
	all arm defconfigs
	all ia64 defconfigs

	alpha alpha-allnoconfig alpha-defconfig alpha-up
	arm
	i386 i386-allnoconfig i386-defconfig i386-up
	ia64 ia64-allnoconfig ia64-defconfig ia64-up
	m68k
	mips
	parisc parisc-allnoconfig parisc-defconfig parisc-up
	powerpc powerpc-up
	s390 s390-allnoconfig s390-defconfig s390-up
	sparc sparc-allnoconfig sparc-defconfig sparc-up
	sparc64 sparc64-allnoconfig sparc64-defconfig sparc64-up
	um-x86_64
	x86_64 x86_64-allnoconfig x86_64-defconfig x86_64-up

as well as my two usual configs.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:45 -07:00
Venki Pallipadi
c5c061b8f9 Add a flag to indicate deferrable timers in /proc/timer_stats
Add a flag in /proc/timer_stats to indicate deferrable timers.  This will
let developers/users to differentiate between types of tiemrs in
/proc/timer_stats.

Deferrable timer and normal timer will appear in /proc/timer_stats as below.
  10D,     1 swapper          queue_delayed_work_on (delayed_work_timer_fn)
   10,     1 swapper          queue_delayed_work_on (delayed_work_timer_fn)

Also version of timer_stats changes from v0.1 to v0.2

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:45 -07:00
Andi Kleen
78c1b06574 Remove clockevents_{release,request}_device
Not called by anything in tree.

Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:43 -07:00
Tomas Janousek
7c3f1a5732 Introduce boot based time
The commits

  411187fb05 (GTOD: persistent clock support)
  c1d370e167 (i386: use GTOD persistent clock
    support)

changed the monotonic time so that it no longer jumps after resume, but it's
not possible to use it for boot time and process start time calculations then.
 Also, the uptime no longer increases during suspend.

I add a variable to track the wall_to_monotonic changes, a function to get the
real boot time and a function to get the boot based time from the monotonic
one.

[akpm@linux-foundation.org: remove exports, add comment]
Signed-off-by: Tomas Janousek <tjanouse@redhat.com>
Cc: Tomas Smetana <tsmetana@redhat.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:41 -07:00
Thomas Gleixner
746976a301 NTP: remove clock_was_set() call to prevent deadlock
The clock_was_set() call in seconds_overflow() which happens only when
leap seconds are inserted / deleted is wrong in two aspects:

1. it results in a call to on_each_cpu() with interrupts disabled
2. it is potential deadlock source vs. call_lock in smp_call_function()

The only possible side effect of the removal might be, that an absolute
CLOCK_REALTIME timer fires 1 second too late, in the rare case of leap
second deletion and an absolute CLOCK_REALTIME timer which expires in
the affected time frame. It will never fire too early.

This was probably observed by the reporter of a June 30th -> July 1st
hang: http://lkml.org/lkml/2007/7/3/103

A similar problem was observed by Dave Jones, who provided a screen shot
with a lockdep back trace, which allowed to analyse the problem.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-03 13:54:27 -07:00
Ingo Molnar
c1a834dc70 timer stats: speedups
Make timer-stats have almost zero overhead when enabled in the config but
not used.  (this way distros can enable it more easily)

Also update the documentation about overhead of timer_stats - it was
written for the first version which had a global lock and a linear list
walk based lookup ;-)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-01 08:18:30 -07:00
Bjorn Steinbrink
9fcc15ec3c timer statistics: fix race
Fix two races in the timer stats lookup code.  One by ensuring that the
initialization of a new entry is finished upon insertion of that entry.
The other by cleaning up the hash table when the entries array is cleared,
so that we don't have any "pre-inserted" entries.

Thanks to Eric Dumazet for reminding me of the memory barriers.

Signed-off-by: Bjorn Steinbrink <B.Steinbrink@gmx.de>
Signed-off-by: Ian Kumlien <pomac@vapor.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-01 08:18:30 -07:00
Thomas Gleixner
eaad084bb0 NOHZ: prevent multiplication overflow - stop timer for huge timeouts
get_next_timer_interrupt() returns a delta of (LONG_MAX > 1) in case
there is no timer pending. On 64 bit machines this results in a
multiplication overflow in tick_nohz_stop_sched_tick().

Reported by: Dave Miller <davem@davemloft.net>

Make the return value a constant and limit the return value to a 32 bit
value.

When the max timeout value is returned, we can safely stop the tick
timer device. The max jiffies delta results in a 12 days timeout for
HZ=1000.

In the long term the get_next_timer_interrupt() code needs to be
reworked to return ktime instead of jiffies, but we have to wait until
the last users of the original NO_IDLE_HZ code are converted.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-29 18:11:10 -07:00
Thomas Gleixner
3528231606 NOHZ: Rate limit the local softirq pending warning output
The warning in the NOHZ code, which triggers when a CPU goes idle with
softirqs pending can fill up the logs quite quickly.  Rate limit the output
until we found the root cause of that problem.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-23 20:14:11 -07:00
Thomas Gleixner
72fcde9662 Ignore bogus ACPI info for offline CPUs
Booting a SMP kernel with maxcpus=1 on a SMP system leads to a hard hang,
because ACPI ignores the maxcpus setting and sends timer broadcast info for
the offline CPUs.  This results in a stuck for ever call to
smp_call_function_single() on an offline CPU.

Ignore the bogus information and print a kernel error to remind ACPI
folks to fix it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-23 20:14:11 -07:00
Alexey Dobriyan
e8edc6e03a Detach sched.h from mm.h
First thing mm.h does is including sched.h solely for can_do_mlock() inline
function which has "current" dereference inside. By dealing with can_do_mlock()
mm.h can be detached from sched.h which is good. See below, why.

This patch
a) removes unconditional inclusion of sched.h from mm.h
b) makes can_do_mlock() normal function in mm/mlock.c
c) exports can_do_mlock() to not break compilation
d) adds sched.h inclusions back to files that were getting it indirectly.
e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
   getting them indirectly

Net result is:
a) mm.h users would get less code to open, read, preprocess, parse, ... if
   they don't need sched.h
b) sched.h stops being dependency for significant number of files:
   on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
   after patch it's only 3744 (-8.3%).

Cross-compile tested on

	all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
	alpha alpha-up
	arm
	i386 i386-up i386-defconfig i386-allnoconfig
	ia64 ia64-up
	m68k
	mips
	parisc parisc-up
	powerpc powerpc-up
	s390 s390-up
	sparc sparc-up
	sparc64 sparc64-up
	um-x86_64
	x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig

as well as my two usual configs.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-21 09:18:19 -07:00
Thomas Gleixner
8f89441b37 clocksource: fix lock order in the resume path
lockdep complains about the lock nesting of clocksource and watchdog lock
in the resume path.

Change the resume marker to a bit operation and remove the lock from this
path.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-15 08:54:00 -07:00
Thomas Gleixner
d10ff3fb62 timekeeping fix patch got mis-applied
The time keeping code move to kernel/time/timekeeping.c broke the
clocksource resume logic patch, which got applied to the old file by a
fuzzy application.  Fix it up and move the clocksource_resume() call to
the appropriate place.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ tssk, tssk, everybody should use --fuzz=0 ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-14 12:13:11 -07:00
Thomas Gleixner
b52f52a093 clocksource: fix resume logic
We need to make sure that the clocksources are resumed, when timekeeping is
resumed.  The current resume logic does not guarantee this.

Add a resume function pointer to the clocksource struct, so clocksource
drivers which need to reinitialize the clocksource can provide a resume
function.

Add a resume function, which calls the maybe available clocksource resume
functions and resets the watchdog function, so a stable TSC can be used
accross suspend/resume.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:56 -07:00
David Miller
9b04bd2756 Fix printk format warnings in timer_list.c
u64 and s64 are not necessarily 'long long' on some 64-bit
platforms, so explicit the type to kill the compiler warnings.

Also consistently use '%Lu' which is unsigned.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:50 -07:00
Daniel Walker
35c35d1afa clocksource: spelling error in watchdog code
There's more that need fixing, and fix my own subject spelling error too.

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:49 -07:00
Siddha, Suresh B
46cb4b7c88 sched: dynticks idle load balancing
Fix the process idle load balancing in the presence of dynticks.  cpus for
which ticks are stopped will sleep till the next event wakes it up.
Potentially these sleeps can be for large durations and during which today,
there is no periodic idle load balancing being done.

This patch nominates an owner among the idle cpus, which does the idle load
balancing on behalf of the other idle cpus.  And once all the cpus are
completely idle, then we can stop this idle load balancing too.  Checks added
in fast path are minimized.  Whenever there are busy cpus in the system, there
will be an owner(idle cpu) doing the system wide idle load balancing.

Open items:
1. Intelligent owner selection (like an idle core in a busy package).
2. Merge with rcu's nohz_cpu_mask?

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Thomas Gleixner
d3ed782458 highres/dyntick: prevent xtime lock contention
While the !highres/!dyntick code assigns the duty of the do_timer() call to
one specific CPU, this was dropped in the highres/dyntick part during
development.

Steven Rostedt discovered the xtime lock contention on highres/dyntick due
to several CPUs trying to update jiffies.

Add the single CPU assignement back.  In the dyntick case this needs to be
handled carefully, as the CPU which has the do_timer() duty must drop the
assignement and let it be grabbed by another CPU, which is active.
Otherwise the do_timer() calls would not happen during the long sleep.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Mark Lord <mlord@pobox.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:10 -07:00
Alexey Dobriyan
9d65cb4a17 Fix race between cat /proc/*/wchan and rmmod et al
kallsyms_lookup() can go iterating over modules list unprotected which is OK
for emergency situations (oops), but not OK for regular stuff like
/proc/*/wchan.

Introduce lookup_symbol_name()/lookup_module_symbol_name() which copy symbol
name into caller-supplied buffer or return -ERANGE.  All copying is done with
module_mutex held, so...

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:08 -07:00
Alexey Dobriyan
ffb4512276 Simplify kallsyms_lookup()
Several kallsyms_lookup() pass dummy arguments but only need, say, module's
name.  Make kallsyms_lookup() accept NULLs where possible.

Also, makes picture clearer about what interfaces are needed for all symbol
resolving business.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:08 -07:00
john stultz
8524070b79 Move timekeeping code to timekeeping.c
Move the timekeeping code out of kernel/timer.c and into
kernel/time/timekeeping.c.  I made no cleanups or other changes in transit.

[akpm@linux-foundation.org: build fix]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:06 -07:00
john stultz
98de9e3ba2 [PATCH] fix jiffies clocksource inittime
In debugging a problem w/ the -rt tree, I noticed that on systems that mark
the tsc as unstable before it is registered, the TSC would still be
selected and used for a short period of time.  Digging in it looks to be a
result of the mix of the clocksource list changes and my clocksource
initialization changes.

With the -rt tree, using a bad TSC, even for a short period of time can
results in a hang at boot.  I was not able to reproduce this hang w/
mainline, but I'm not completely certain that someone won't trip on it.

This patch resolves the issue by initializing the jiffies clocksource
earlier so a bad TSC won't get selected just because nothing else is yet
registered.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-04 21:12:47 -07:00
john stultz
d62ac21aa0 [PATCH] ntp: avoid time_offset overflows
I've been seeing some odd NTP behavior recently on a few boxes and
finally narrowed it down to time_offset overflowing when converted to
SHIFT_UPDATE units (which was a side effect from my HZfreeNTP patch).

This patch converts time_offset from a long to a s64 which resolves the
issue.

[tglx@linutronix.de: signedness fixes]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-27 09:05:15 -07:00
Thomas Gleixner
291bc047e1 [PATCH] clockevents: remove bad designed sysfs support for now
The current sysfs support of clockevents does not obey the "only one
value per file" rule.

The real fix is not 2.6.21 material. Therefor remove the sysfs support
for now.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-26 14:07:23 -07:00