25 Apr, 2008
1 commit
-
David Miller reported:
|--------------->
the following commit:| commit 27ec4407790d075c325e1f4da0a19c56953cce23
| Author: Ingo Molnar
| Date: Thu Feb 28 21:00:21 2008 +0100
|
| sched: make cpu_clock() globally synchronous
|
| Alexey Zaytsev reported (and bisected) that the introduction of
| cpu_clock() in printk made the timestamps jump back and forth.
|
| Make cpu_clock() more reliable while still keeping it fast when it's
| called frequently.
|
| Signed-off-by: Ingo Molnarcauses watchdog triggers when a cpu exits NOHZ state when it has been
there for >= the soft lockup threshold, for example here are some
messages from a 128 cpu Niagara2 box:[ 168.106406] BUG: soft lockup - CPU#11 stuck for 128s! [dd:3239]
[ 168.989592] BUG: soft lockup - CPU#21 stuck for 86s! [swapper:0]
[ 168.999587] BUG: soft lockup - CPU#29 stuck for 91s! [make:4511]
[ 168.999615] BUG: soft lockup - CPU#2 stuck for 85s! [swapper:0]
[ 169.020514] BUG: soft lockup - CPU#37 stuck for 91s! [swapper:0]
[ 169.020514] BUG: soft lockup - CPU#45 stuck for 91s! [sh:4515]
[ 169.020515] BUG: soft lockup - CPU#69 stuck for 92s! [swapper:0]
[ 169.020515] BUG: soft lockup - CPU#77 stuck for 92s! [swapper:0]
[ 169.020515] BUG: soft lockup - CPU#61 stuck for 92s! [swapper:0]
[ 169.112554] BUG: soft lockup - CPU#85 stuck for 92s! [swapper:0]
[ 169.112554] BUG: soft lockup - CPU#101 stuck for 92s! [swapper:0]
[ 169.112554] BUG: soft lockup - CPU#109 stuck for 92s! [swapper:0]
[ 169.112554] BUG: soft lockup - CPU#117 stuck for 92s! [swapper:0]
[ 169.171483] BUG: soft lockup - CPU#40 stuck for 80s! [dd:3239]
[ 169.331483] BUG: soft lockup - CPU#13 stuck for 86s! [swapper:0]
[ 169.351500] BUG: soft lockup - CPU#43 stuck for 101s! [dd:3239]
[ 169.531482] BUG: soft lockup - CPU#9 stuck for 129s! [mkdir:4565]
[ 169.595754] BUG: soft lockup - CPU#20 stuck for 93s! [swapper:0]
[ 169.626787] BUG: soft lockup - CPU#52 stuck for 93s! [swapper:0]
[ 169.626787] BUG: soft lockup - CPU#84 stuck for 92s! [swapper:0]
[ 169.636812] BUG: soft lockup - CPU#116 stuck for 94s! [swapper:0]It's simple enough to trigger this by doing a 10 minute sleep after a
fresh bootup then starting a parallel kernel build.I suspect this might be reintroducing a problem we've had and fixed
before, see the thread:http://marc.info/?l=linux-kernel&m=119546414004065&w=2
22 Apr, 2008
2 commits
-
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt:
hrtimer: optimize the softirq time optimization
hrtimer: reduce calls to hrtimer_get_softirq_time()
clockevents: fix typo in tick-broadcast.c
jiffies: add time_is_after_jiffies and others which compare with jiffies -
…linux-2.6-sched-devel
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-devel: (62 commits)
sched: build fix
sched: better rt-group documentation
sched: features fix
sched: /debug/sched_features
sched: add SCHED_FEAT_DEADLINE
sched: debug: show a weight tree
sched: fair: weight calculations
sched: fair-group: de-couple load-balancing from the rb-trees
sched: fair-group scheduling vs latency
sched: rt-group: optimize dequeue_rt_stack
sched: debug: add some debug code to handle the full hierarchy
sched: fair-group: SMP-nice for group scheduling
sched, cpuset: customize sched domains, core
sched, cpuset: customize sched domains, docs
sched: prepatory code movement
sched: rt: multi level group constraints
sched: task_group hierarchy
sched: fix the task_group hierarchy for UID grouping
sched: allow the group scheduler to have multiple levels
sched: mix tasks and groups
...
21 Apr, 2008
1 commit
-
braodcast -> broadcast
Signed-off-by: Glauber Costa
Signed-off-by: Andrew Morton
Signed-off-by: Thomas Gleixner
20 Apr, 2008
2 commits
-
Various SMP balancing algorithms require that the bandwidth period
run in sync.Possible improvements are moving the rt_bandwidth thing into root_domain
and keeping a span per rt_bandwidth which marks throttled cpus.Signed-off-by: Peter Zijlstra
Signed-off-by: Ingo Molnar -
We already catch most of the TSC problems by sanity checks, but there
is a subtle bug which has been in the code forever. This can cause
time jumps in the range of hours.This was reported in:
http://lkml.org/lkml/2007/8/23/96
and
http://lkml.org/lkml/2008/3/31/23I was able to reproduce the problem with a gettimeofday loop test on a
dual core and a quad core machine which both have sychronized
TSCs. The TSCs seems not to be perfectly in sync though, but the
kernel is not able to detect the slight delta in the sync check. Still
there exists an extremly small window where this delta can be observed
with a real big time jump. So far I was only able to reproduce this
with the vsyscall gettimeofday implementation, but in theory this
might be observable with the syscall based version as well.CPU 0 updates the clock source variables under xtime/vyscall lock and
CPU1, where the TSC is slighty behind CPU0, is reading the time right
after the seqlock was unlocked.The clocksource reference data was updated with the TSC from CPU0 and
the value which is read from TSC on CPU1 is less than the reference
data. This results in a huge delta value due to the unsigned
subtraction of the TSC value and the reference value. This algorithm
can not be changed due to the support of wrapping clock sources like
pm timer.The huge delta is converted to nanoseconds and added to xtime, which
is then observable by the caller. The next gettimeofday call on CPU1
will show the correct time again as now the TSC has advanced above the
reference value.To prevent this TSC specific wreckage we need to compare the TSC value
against the reference value and return the latter when it is larger
than the actual TSC value.I pondered to mark the TSC unstable when the readout is smaller than
the reference value, but this would render an otherwise good and fast
clocksource unusable without a real good reason.Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar
18 Apr, 2008
3 commits
-
* git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt:
clocksource: make clocksource watchdog cycle through online CPUs
Documentation: move timer related documentation to a single place
clockevents: optimise tick_nohz_stop_sched_tick() a bit
locking: remove unused double_spin_lock()
hrtimers: simplify lockdep handling
timers: simplify lockdep handling
posix-timers: fix shadowed variables
timer_list: add annotations to workqueue.c
hrtimer: use nanosleep specific restart_block fields
hrtimer: add nanosleep specific restart_block member -
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb:
kgdb: always use icache flush for sw breakpoints
kgdb: fix SMP NMI kgdb_handle_exception exit race
kgdb: documentation fixes
kgdb: allow static kgdbts boot configuration
kgdb: add documentation
kgdb: Kconfig fix
kgdb: add kgdb internal test suite
kgdb: fix several kgdb regressions
kgdb: kgdboc pl011 I/O module
kgdb: fix optional arch functions and probe_kernel_*
kgdb: add x86 HW breakpoints
kgdb: print breakpoint removed on exception
kgdb: clocksource watchdog
kgdb: fix NMI hangs
kgdb: fix kgdboc dynamic module configuration
kgdb: document parameters
x86: kgdb support
consoles: polling support, kgdboc
kgdb: core
uaccess: add probe_kernel_write() -
In order to not trip the clocksource watchdog, kgdb must touch the
clocksource watchdog on the return to normal system run state.Signed-off-by: Jason Wessel
Signed-off-by: Ingo Molnar
17 Apr, 2008
3 commits
-
This way it checks if the clocks are synchronized between CPUs too.
This might be able to detect slowly drifting TSCs which only
go wrong over longer time.Signed-off-by: Andi Kleen
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
Call
ts = &per_cpu(tick_cpu_sched, cpu);
and
cpu = smp_processor_id();
once instead of twice.No functional change done, as changed code runs with local irq off.
Reduces source lines and text size (20bytes on x86_64).[ akpm@linux-foundation.org: Build fix ]
Signed-off-by: Karsten Wiese
Cc: Andrew Morton
Signed-off-by: Thomas Gleixner -
> Generic code is not supposed to include irq.h. Replace this include
> by linux/hardirq.h instead and add/replace an include of linux/irq.h
> in asm header files where necessary.
> This change should only matter for architectures that make use of
> GENERIC_CLOCKEVENTS.
> Architectures in question are mips, x86, arm, sh, powerpc, uml and sparc64.
>
> I did some cross compile tests for mips, x86_64, arm, powerpc and sparc64.
> This patch fixes also build breakages caused by the include replacement in
> tick-common.h.I generally dislike adding optional linux/* includes in asm/* includes -
I'm nervous about this causing include loops.However, there's a separate point to be discussed here.
That is, what interfaces are expected of every architecture in the kernel.
If generic code wants to be able to set the affinity of interrupts, then
that needs to become part of the interfaces listed in linux/interrupt.h
rather than linux/irq.h.So what I suggest is this approach instead (against Linus' tree of a
couple of days ago) - we move irq_set_affinity() and irq_can_set_affinity()
to linux/interrupt.h, change the linux/irq.h includes to linux/interrupt.h
and include asm/irq_regs.h where needed (asm/irq_regs.h is supposed to be
rarely used include since not much touches the stacked parent context
registers.)Build tested on ARM PXA family kernels and ARM's Realview platform
kernels which both use genirq.[ tglx@linutronix.de: add GENERIC_HARDIRQ dependencies ]
Signed-off-by: Russell King
Signed-off-by: Thomas Gleixner
Signed-off-by: Martin Schwidefsky
Signed-off-by: Heiko Carstens
26 Mar, 2008
1 commit
-
Revert
commit 1077f5a917b7c630231037826b344b2f7f5b903f
Author: Parag Warudkar
Date: Wed Jan 30 13:30:01 2008 +0100clocksource.c: use init_timer_deferrable for clocksource_watchdog
clocksource_watchdog can use a deferrable timer - reduces wakeups from
idle per second.The watchdog timer needs to run with the specified interval. Otherwise
it will miss the possible wrap of the watchdog clocksource.Signed-off-by: Thomas Gleixner
Cc: stable@kernel.org
25 Mar, 2008
1 commit
-
The printk() can deadlock because it can wake up klogd(), and
task enqueueing will try to read the time in order to set a hrtimer.Reported-by: Marcin Slusarz
Debugged-by: Peter Zijlstra
Cc: Ingo Molnar
Cc: Thomas Gleixner
Signed-off-by: Linus Torvalds
20 Mar, 2008
1 commit
-
Revert commit 1ada5cba6a0318f90e45b38557e7b5206a9cba38 ("clocksource:
make clocksource watchdog cycle through online CPUs") due to the
regression reported by Gabriel C athttp://lkml.org/lkml/2008/2/24/281
(short vesion: it makes TSC be marked as always unstable on his
machine).Cc: Andi Kleen
Acked-by: Ingo Molnar
Cc: Thomas Gleixner
Cc: Robert Hancock
Acked-by: Linus Torvalds
Cc: "Rafael J. Wysocki"
Cc: Gabriel C
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Mar, 2008
3 commits
-
The first version of the ntp_interval/tick_length inconsistent usage patch was
recently merged as bbe4d18ac2e058c56adb0cd71f49d9ed3216a405http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bbe4d18ac2e058c56adb0cd71f49d9ed3216a405
While the fix did greatly improve the situation, it was correctly pointed out
by Roman that it does have a small bug: If the users change clocksources after
the system has been running and NTP has made corrections, the correctoins made
against the old clocksource will be applied against the new clocksource,
causing error.The second attempt, which corrects the issue in the NTP_INTERVAL_LENGTH
definition has also made it up-stream as commit
e13a2e61dd5152f5499d2003470acf9c838eab84http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e13a2e61dd5152f5499d2003470acf9c838eab84
Roman has correctly pointed out that CLOCK_TICK_ADJUST is calculated
based on the PIT's frequency, and isn't really relevant to non-PIT
driven clocksources (that is, clocksources other then jiffies and pit).This patch reverts both of those changes, and simply removes
CLOCK_TICK_ADJUST.This does remove the granularity error correction for users of PIT and Jiffies
clocksource users, but the granularity error but for the majority of users, it
should be within the 500ppm range NTP can accommodate for.For systems that have granularity errors greater then 500ppm, the
"ntp_tick_adj=" boot option can be used to compensate.[johnstul@us.ibm.com: provided changelog]
[mattilinnanvuori@yahoo.com: maek ntp_tick_adj static]
Signed-off-by: Roman Zippel
Acked-by: john stultz
Signed-off-by: Matti Linnanvuori
Signed-off-by: Andrew Morton
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner -
Silences WARN_ONs in rcu_enter_nohz() and rcu_exit_nohz(), which appeared
before caused by (repeated) calls to:
$ echo 0 > /sys/devices/system/cpu/cpu1/online
$ echo 1 > /sys/devices/system/cpu/cpu1/onlineSigned-off-by: Karsten Wiese
Cc: johnstul@us.ibm.com
Cc: Rafael Wysocki
Cc: Steven Rostedt
Cc: Ingo Molnar
Acked-by: Paul E. McKenney
Signed-off-by: Andrew Morton
Signed-off-by: Thomas Gleixner -
The kernel NTP code shouldn't hand 64-bit *signed* values to do_div(). Make it
instead hand 64-bit unsigned values. This gets rid of a couple of warnings.Signed-off-by: David Howells
Cc: Roman Zippel
Cc: Ingo Molnar
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Thomas Gleixner
01 Mar, 2008
1 commit
-
The PREEMPT-RCU can get stuck if a CPU goes idle and NO_HZ is set. The
idle CPU will not progress the RCU through its grace period and a
synchronize_rcu my get stuck. Without this patch I have a box that will
not boot when PREEMPT_RCU and NO_HZ are set. That same box boots fine
with this patch.This patch comes from the -rt kernel where it has been tested for
several months.Signed-off-by: Steven Rostedt
Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar
18 Feb, 2008
1 commit
-
Relative expiry time can get negative, so it should be signed.
Signed-off-by: Pavel Machek
Signed-off-by: Thomas Gleixner
10 Feb, 2008
1 commit
-
clocksource initialization and error accumulation. This corrects a 280ppm
drift seen on some systems using acpi_pm, and affects other clocksources as
well (likely to a lesser degree).Signed-off-by: John Stultz
Cc: Roman Zippel
Cc: Steven Rostedt
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
09 Feb, 2008
4 commits
-
Fix typo in comments.
BTW: I have to fix coding style in arch/ia64/kernel/time.c also, otherwise
checkpatch.pl will be complaining.Signed-off-by: Li Zefan
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Function timekeeping_is_continuous() no longer checks flag
CLOCK_IS_CONTINUOUS, and it checks CLOCK_SOURCE_VALID_FOR_HRES now. So rename
the function accordingly.Signed-off-by: Li Zefan
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
list_for_each_safe() suffices here.
Signed-off-by: Li Zefan
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Flag CLOCK_SOURCE_WATCHDOG is cleared twice. Note clocksource_change_rating()
won't do anyting with the cs flag.Signed-off-by: Li Zefan
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
07 Feb, 2008
1 commit
-
I found that there is a buffer overflow problem in the following code.
Version: 2.6.24-rc2,
File: kernel/time/clocksource.c:417-432
--------------------------------------------------------------------
static ssize_t
sysfs_show_available_clocksources(struct sys_device *dev, char *buf)
{
struct clocksource *src;
char *curr = buf;spin_lock_irq(&clocksource_lock);
list_for_each_entry(src, &clocksource_list, list) {
curr += sprintf(curr, "%s ", src->name);
}
spin_unlock_irq(&clocksource_lock);curr += sprintf(curr, "\n");
return curr - buf;
}
-----------------------------------------------------------------------sysfs_show_current_clocksources() also has the same problem though in practice
the size of current clocksource's name won't exceed PAGE_SIZE.I fix the bug by using snprintf according to the specification of the kernel
(Version:2.6.24-rc2,File:Documentation/filesystems/sysfs.txt)Fix sysfs_show_available_clocksources() and sysfs_show_current_clocksources()
buffer overflow problem with snprintf().Signed-off-by: Miao Xie
Cc: WANG Cong
Cc: Thomas Gleixner
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
02 Feb, 2008
2 commits
-
To allow better diagnosis of tick-sched related, especially NOHZ
related problems, we need to know when the last wakeup via an irq
happened and when the CPU left the idle state.Add two fields (idle_waketime, idle_exittime) to the tick_sched
structure and add them to the timer_list output.Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar -
xtime_cache needs to be updated whenever xtime and or wall_to_monotic
are changed. Otherwise users of xtime_cache might see a stale (and in
the case of timezone changes utterly wrong) value until the next
update happens.Fixup the obvious places, which miss this update.
Signed-off-by: Thomas Gleixner
Acked-by: John Stultz
Tested-by: Dhaval Giani
Signed-off-by: Ingo Molnar
30 Jan, 2008
10 commits
-
Current idle time in kstat is based on jiffies and is coarse grained.
tick_sched.idle_sleeptime is making some attempt to keep track of idle time
in a fine grained manner. But, it is not handling the time spent in
interrupts fully.Make tick_sched.idle_sleeptime accurate with respect to time spent on
handling interrupts and also add tick_sched.idle_lastupdate, which keeps
track of last time when idle_sleeptime was updated.This statistics will be crucial for cpufreq-ondemand governor, which can
shed some conservative gaurd band that is uses today while setting the
frequency. The ondemand changes that uses the exact idle time is coming
soon.Signed-off-by: Venkatesh Pallipadi
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
I recently noticed on one of my boxes that when synched with an NTP
server, the drift value reported for the system was ~283ppm. While in
some cases, clock hardware can be that bad, it struck me as unusual as
the system was using the acpi_pm clocksource, which is one of the more
trustworthy and accurate clocksources on x86 hardware.I brought up another system and let it sync to the same NTP server, and
I noticed a similar 280some ppm drift.In looking at the code, I found that the acpi_pm's constant frequency
was being computed correctly at boot-up, however once the system was up,
even without the ntp daemon running, the clocksource's frequency was
being modified by the clocksource_adjust() function.Digging deeper, I realized that in the code that keeps track of how much
the clocksource is skewing from the ntp desired time, we were using
different lengths to establish how long an time interval was.The clocksource was being setup with the following interval:
NTP_INTERVAL_LENGTH = NSEC_PER_SEC/NTP_INTERVAL_FREQWhile the ntp code was using the tick_length_base value:
tick_length_base ~= (tick_usec * NSEC_PER_USEC * USER_HZ)
/NTP_INTERVAL_FREQThe subtle difference is:
(tick_usec * NSEC_PER_USEC * USER_HZ) != NSEC_PER_SECThis difference in calculation was causing the clocksource correction
code to apply a correction factor to the clocksource so the two
intervals were the same, however this results in the actual frequency of
the clocksource to be made incorrect. I believe this difference would
affect all clocksources, although to differing degrees depending on the
clocksource resolution.The issue was introduced when my HZ free ntp patch landed in 2.6.21-rc1,
so my apologies for the mistake, and for not noticing it until now.The following patch, corrects the clocksource's initialization code so
it uses the same interval length as the code in ntp.c. After applying
this patch, the drift value for the same system went from ~283ppm to
only 2.635ppm.I believe this patch to be good, however it does affect all arches and
I've only tested on x86, so some caution is advised. I do think it would
be a likely candidate for a stable 2.6.24.x release.Any thoughts or feedback would be appreciated.
Signed-off-by: John Stultz
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
detect zero event-device multiplicators - they then cause
division-by-zero crashes if a clockevent has been initialized
incorrectly.Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
On x86 the PIT might become an unusable clocksource. Add an unregister
function to provide a possibilty to remove the PIT from the list of
available clock sources.Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar -
This way it checks if the clocks are synchronized between CPUs too.
This might be able to detect slowly drifting TSCs which only
go wrong over longer time.Signed-off-by: Andi Kleen
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
clocksource_watchdog can use a deferrable timer - reduces wakeups from
idle per second.Signed-off-by: Parag Warudkar
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
- getnstimeofday() was just a wrapper around __get_realtime_clock_ts()
- Replace calls to __get_realtime_clock_ts() by calls to getnstimeofday()
- Fix bogus reference to get_realtime_clock_ts(), which never existedSigned-off-by: Geert Uytterhoeven
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
clean up tick-broadcast.c
Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar -
I was confused by FSEC = 10^15 NSEC statement, plus small whitespace
fixes. When there's copyright, there should be GPL.Signed-off-by: Pavel Machek
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
Small cleanups to tick-related code. Wrong preempt count is followed
by BUG(), so it is hardly KERN_WARNING.Signed-off-by: Pavel Machek
Cc: john stultz
Signed-off-by: Andrew Morton
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
26 Jan, 2008
2 commits
-
In order to more easily allow for the scheduler to use timers, clean up
the locking a bit.Signed-off-by: Peter Zijlstra
Signed-off-by: Ingo Molnar -
We need to teach no_hz about the rt throttling because its tick driven.
Signed-off-by: Peter Zijlstra
Signed-off-by: Ingo Molnar