22 Aug, 2009
2 commits
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After talking with some application writers who want very fast, but not
fine-grained timestamps, I decided to try to implement new clock_ids
to clock_gettime(): CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE
which returns the time at the last tick. This is very fast as we don't
have to access any hardware (which can be very painful if you're using
something like the acpi_pm clocksource), and we can even use the vdso
clock_gettime() method to avoid the syscall. The only trade off is you
only get low-res tick grained time resolution.This isn't a new idea, I know Ingo has a patch in the -rt tree that made
the vsyscall gettimeofday() return coarse grained time when the
vsyscall64 sysctrl was set to 2. However this affects all applications
on a system.With this method, applications can choose the proper speed/granularity
trade-off for themselves.Signed-off-by: John Stultz
Cc: Andi Kleen
Cc: nikolag@ca.ibm.com
Cc: Darren Hart
Cc: arjan@infradead.org
Cc: jonathan@jonmasters.org
LKML-Reference:
Signed-off-by: Thomas Gleixner -
This basically reverts commit 1a0c009ac (x86: unregister PIT
clocksource when PIT is disabled) because the problem which was tried
to address with that patch has been solved by commit 3f68535ada
(clocksource: sanity check sysfs clocksource changes).The problem addressed by the original patch is that PIT could be
selected as clocksource after the system switched the PIT off or set
the PIT into one shot mode which would result in complete timekeeping
wreckage.Now with the sysfs sanity check in place PIT cannot be selected again
when the system is in oneshot mode. The system will not switch to one
shot mode as long as PIT is installed because PIT is not suitable for
one shot.The shutdown case which happens when the lapic timer is installed is
covered by the fact that init_pit_clocksource() is called after the
lapic timer take over and then does not install the PIT clocksource
at all.We should have done the sanity checks back then, but ...
This also solves the locking problem which was reported vs. the
clocksource rework.LKML-Reference:
Cc: Martin Schwidefsky
Cc: john stultz
Signed-off-by: Thomas Gleixner
19 Aug, 2009
2 commits
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stop_machine from a multithreaded workqueue is not allowed because
of a circular locking dependency between cpu_down and the workqueue
execution. Use a kernel thread to do the clocksource downgrade.Signed-off-by: Martin Schwidefsky
Cc: Peter Zijlstra
Cc: john stultz
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Martin pointed out that commit 6ea41d2529 (clocksource: Call
clocksource_change_rating() outside of watchdog_lock) has a
theoretical reference count problem. The calls to
clocksource_change_rating() are now done outside of the clocksource
mutex and outside of the watchdog lock. A concurrent
clocksource_unregister() could remove the clock.Split out the code which changes the rating from
clocksource_change_rating() into __clocksource_change_rating().Protect the clocksource_watchdog_work() code sequence with the
clocksource_mutex() and call __clocksource_change_rating().LKML-Reference:
Signed-off-by: Thomas Gleixner
Cc: Martin Schwidefsky
15 Aug, 2009
16 commits
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The changes to the watchdog logic introduced a lock inversion between
watchdog_lock and clocksource_mutex. Change the rating outside of
watchdog_lock to avoid it.Signed-off-by: Thomas Gleixner
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Add the new function read_boot_clock to get the exact time the system
has been started. For architectures without support for exact boot
time a new weak function is added that returns 0. Use the exact boot
time to initialize wall_to_monotonic, or xtime if the read_boot_clock
returned 0.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The persistent clock of some architectures (e.g. s390) have a
better granularity than seconds. To reduce the delta between the
host clock and the guest clock in a virtualized system change the
read_persistent_clock function to return a struct timespec.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
update_wall_time calls change_clocksource HZ times per second to check
if a new clock source is available. In close to 100% of all calls
there is no new clock. Replace the tick based check by an update done
with stop_machine.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Add timekeeper_read_clock_ntp and timekeeper_read_clock_raw and use
them for getnstimeofday, ktime_get, ktime_get_ts and getrawmonotonic.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The clocksource structure has two multipliers, the unmodified multiplier
clock->mult_orig and the NTP corrected multiplier clock->mult. The NTP
multiplier is misplaced in the struct clocksource, this is private
information of the timekeeping code. Add the mult field to the struct
timekeeper to contain the NTP corrected value, keep the unmodifed
multiplier in clock->mult and remove clock->mult_orig.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The xtime_nsec value in the timekeeper structure is shifted by a few
bits to improve precision. This happens to be the same value as the
clock->shift. To improve readability add xtime_shift to the timekeeper
and use it instead of the clock->shift. Likewise add ntp_error_shift
and replace all (NTP_SCALE_SHIFT - clock->shift) expressions.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Add struct timekeeper to keep the internal values timekeeping.c needs
in regard to the currently selected clock source. This moves the
timekeeping intervals, xtime_nsec and the ntp error value from struct
clocksource to struct timekeeper. The raw_time is removed from the
clocksource as well. It gets treated like xtime as a global variable.
Eventually xtime raw_time should be moved to struct timekeeper.[ tglx: minor cleanup ]
Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Move the downgrade of an unstable clocksource from the timer interrupt
context into the process context of a work queue thread. This is
needed to be able to do the clocksource switch with stop_machine.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Refactor clocksource watchdog code to make it more readable. Add
clocksource_dequeue_watchdog to remove a clocksource from the watchdog
list when it is unregistered.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
To resume the clocksource watchdog just remove the CLOCK_SOURCE_WATCHDOG
bit from the watched clocksource.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The clocksource watchdog marks a clock as highres capable before it
checked the deviation from the watchdog clocksource even for a single
time. Make sure that the deviation is at least checked once before
doing the switch to highres mode.Signed-off-by: Martin Schwidefsky
Cc: Ingo Molnar
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
If a non high-resolution clocksource is first set as override clock
and then registered it becomes active even if the system is in one-shot
mode. Move the override check from sysfs_override_clocksource to the
clocksource selection. That fixes the bug and simplifies the code. The
check in clocksource_register for double registration of the same
clocksource is removed without replacement.To find the initial clocksource a new weak function in jiffies.c is
defined that returns the jiffies clocksource. The architecture code
can then override the weak function with a more suitable clocksource,
e.g. the TOD clock on s390.[ tglx: Folded in a fix from John Stultz ]
Signed-off-by: Martin Schwidefsky
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
change_clocksource resets the cycle_last value to zero then sets it to
a value read from the clocksource. The reset to zero is required only
for the TSC clocksource to make the read_tsc function work after a
resume. The reason is that the TSC read function uses cycle_last to
detect backwards going TSCs. In the resume case cycle_last contains
the TSC value from the last update before the suspend. On resume the
TSC starts counting from 0 again and would trip over the cycle_last
comparison.This is subtle and surprising. Move the reset to a resume function in
the tsc code.Signed-off-by: Martin Schwidefsky
Acked-by: Thomas Gleixner
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
The three inline functions clocksource_read, clocksource_enable and
clocksource_disable are simple wrappers of an indirect call plus the
copy from and to the mult_orig value. The functions are exclusively
used by the timekeeping code which has intimate knowledge of the
clocksource anyway. Therefore remove the inline functions. No
functional change.Signed-off-by: Martin Schwidefsky
Acked-by: John Stultz
Cc: Daniel Walker
LKML-Reference:
Signed-off-by: Thomas Gleixner -
Move the adjustment of xtime, wall_to_monotonic and the update of the
vsyscall variables to the timekeeping code.Signed-off-by: John Stultz
Signed-off-by: Martin Schwidefsky
LKML-Reference:
Signed-off-by: Thomas Gleixner
14 Aug, 2009
10 commits
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Reason: Martin's timekeeping cleanup series depends on both
timers/core and mainline changes.Signed-off-by: Thomas Gleixner
-
free_irq() can remove an irqaction while the corresponding interrupt
is in progress, but free_irq() sets action->thread to NULL
unconditionally, which might lead to a NULL pointer dereference in
handle_IRQ_event() when the hard interrupt context tries to wake up
the handler thread.Prevent this by moving the thread stop after synchronize_irq(). No
need to set action->thread to NULL either as action is going to be
freed anyway.This fixes a boot crash reported against preempt-rt which uses the
mainline irq threads code to implement full irq threading.[ tglx: removed local irqthread variable ]
Signed-off-by: Linus Torvalds
Signed-off-by: Thomas Gleixner -
…x/kernel/git/tip/linux-2.6-tip
* 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf_counter: Report the cloning task as parent on perf_counter_fork()
perf_counter: Fix an ipi-deadlock
perf: Rework/fix the whole read vs group stuff
perf_counter: Fix swcounter context invariance
perf report: Don't show unresolved DSOs and symbols when -S/-d is used
perf tools: Add a general option to enable raw sample records
perf tools: Add a per tracepoint counter attribute to get raw sample
perf_counter: Provide hw_perf_counter_setup_online() APIs
perf list: Fix large list output by using the pager
perf_counter, x86: Fix/improve apic fallback
perf record: Add missing -C option support for specifying profile cpu
perf tools: Fix dso__new handle() to handle deleted DSOs
perf tools: Fix fallback to cplus_demangle() when bfd_demangle() is not available
perf report: Show the tid too in -D
perf record: Fix .tid and .pid fill-in when synthesizing events
perf_counter, x86: Fix generic cache events on P6-mobile CPUs
perf_counter, x86: Fix lapic printk message -
…/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
futex: Fix handling of bad requeue syscall pairing
futex: Fix compat_futex to be same as futex for REQUEUE_PI
locking, sched: Give waitqueue spinlocks their own lockdep classes
futex: Update futex_q lock_ptr on requeue proxy lock -
…git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Fix oops in identify_cpu() on CPUs without CPUID
x86: Clear incorrectly forced X86_FEATURE_LAHF_LM flag
x86, mce: therm_throt - change when we print messages
x86: Add reboot quirk for every 5 series MacBook/Pro -
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2: (22 commits)
ocfs2: Fix possible deadlock when extending quota file
ocfs2: keep index within status_map[]
ocfs2: Initialize the cluster we're writing to in a non-sparse extend
ocfs2: Remove redundant BUG_ON in __dlm_queue_ast()
ocfs2/quota: Release lock for error in ocfs2_quota_write.
ocfs2: Define credit counts for quota operations
ocfs2: Remove syncjiff field from quota info
ocfs2: Fix initialization of blockcheck stats
ocfs2: Zero out padding of on disk dquot structure
ocfs2: Initialize blocks allocated to local quota file
ocfs2: Mark buffer uptodate before calling ocfs2_journal_access_dq()
ocfs2: Make global quota files blocksize aligned
ocfs2: Use ocfs2_rec_clusters in ocfs2_adjust_adjacent_records.
ocfs2: Fix deadlock on umount
ocfs2: Add extra credits and access the modified bh in update_edge_lengths.
ocfs2: Fail ocfs2_get_block() immediately when a block needs allocation
ocfs2: Fix error return in ocfs2_write_cluster()
ocfs2: Fix compilation warning for fs/ocfs2/xattr.c
ocfs2: Initialize count in aio_write before generic_write_checks
ocfs2: log the actual return value of ocfs2_file_aio_write()
... -
* 'for-linus' of git://neil.brown.name/md:
md: allow upper limit for resync/reshape to be set when array is read-only
md/raid5: Properly remove excess drives after shrinking a raid5/6
md/raid5: make sure a reshape restarts at the correct address.
md/raid5: allow new reshape modes to be restarted in the middle.
md: never advance 'events' counter by more than 1.
Remove deadlock potential in md_open -
* 'sh/for-2.6.31' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6:
sh: fix i2c init order on ap325rxa V2
sh: fix i2c init order on Migo-R V2
sh: convert processor device setup functions to arch_initcall() -
kernel_sendpage() does the proper default case handling for when the
socket doesn't have a native sendpage implementation.Now, arguably this might be something that we could instead solve by
just specifying that all protocols should do it themselves at the
protocol level, but we really only care about the common protocols.
Does anybody really care about sendpage on something like Appletalk? Not
likely.Acked-by: David S. Miller
Acked-by: Julien TINNES
Acked-by: Tavis Ormandy
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
13 Aug, 2009
10 commits
-
A bug in (9f498cc: perf_counter: Full task tracing) makes
profiling multi-threaded apps it go belly up.[ output as: (PID:TID):(PPID:PTID) ]
# ./perf report -D | grep FORK
0x4b0 [0x18]: PERF_EVENT_FORK: (3237:3237):(3236:3236)
0xa10 [0x18]: PERF_EVENT_FORK: (3237:3238):(3236:3236)
0xa70 [0x18]: PERF_EVENT_FORK: (3237:3239):(3236:3236)
0xad0 [0x18]: PERF_EVENT_FORK: (3237:3240):(3236:3236)
0xb18 [0x18]: PERF_EVENT_FORK: (3237:3241):(3236:3236)Shows us that the test (27d028d perf report: Update for the new
FORK/EXIT events) in builtin-report.c:/*
* A thread clone will have the same PID for both
* parent and child.
*/
if (thread == parent)
return 0;Will clearly fail.
The problem is that perf_counter_fork() reports the actual
parent, instead of the cloning thread.Fixing that (with the below patch), yields:
# ./perf report -D | grep FORK
0x4c8 [0x18]: PERF_EVENT_FORK: (1590:1590):(1589:1589)
0xbd8 [0x18]: PERF_EVENT_FORK: (1590:1591):(1590:1590)
0xc80 [0x18]: PERF_EVENT_FORK: (1590:1592):(1590:1590)
0x3338 [0x18]: PERF_EVENT_FORK: (1590:1593):(1590:1590)
0x66b0 [0x18]: PERF_EVENT_FORK: (1590:1594):(1590:1590)Which both makes more sense and doesn't confuse perf report
anymore.Reported-by: Pekka Enberg
Signed-off-by: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: paulus@samba.org
Cc: Anton Blanchard
Cc: Arjan van de Ven
LKML-Reference:
Signed-off-by: Ingo Molnar -
perf_pending_counter() is called from IRQ context and will call
perf_counter_disable(), however perf_counter_disable() uses
smp_call_function_single() which doesn't fancy being used with
IRQs disabled due to IPI deadlocks.Fix this by making it use the local __perf_counter_disable()
call and teaching the counter_sched_out() code about pending
disables as well.This should cover the case where a counter migrates before the
pending queue gets processed.Signed-off-by: Peter Zijlstra
Cc: Corey J Ashford
Cc: Paul Mackerras
Cc: stephane eranian
LKML-Reference:
Signed-off-by: Ingo Molnar -
Replace PERF_SAMPLE_GROUP with PERF_SAMPLE_READ and introduce
PERF_FORMAT_GROUP to deal with group reads in a more generic
way.This allows you to get group reads out of read() as well.
Signed-off-by: Peter Zijlstra
Cc: Corey J Ashford
Cc: Paul Mackerras
Cc: stephane eranian
LKML-Reference:
Signed-off-by: Ingo Molnar -
perf_swcounter_is_counting() uses a lock, which means we cannot
use swcounters from NMI or when holding that particular lock,
this is unintended.The below removes the lock, this opens up race window, but not
worse than the swcounters already experience due to RCU
traversal of the context in perf_swcounter_ctx_event().This also fixes the hard lockups while opening a lockdep
tracepoint counter.Signed-off-by: Peter Zijlstra
Acked-by: Frederic Weisbecker
Cc: Paul Mackerras
Cc: stephane eranian
Cc: Corey J Ashford
LKML-Reference:
Signed-off-by: Ingo Molnar -
We're interested in just those symbols/DSOs, so filter out the
unresolved ones.Signed-off-by: Arnaldo Carvalho de Melo
Cc: Peter Zijlstra
LKML-Reference:
Signed-off-by: Ingo Molnar -
While we can enable the perf sample records per tracepoint
counter, we may also want to enable this option for every
tracepoint counters to open, so that we don't need to add a
:record flag for all of them.Add the -R, --raw-samples options for this purpose.
Signed-off-by: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Mike Galbraith
LKML-Reference:
Signed-off-by: Ingo Molnar -
Add a new flag field while opening a tracepoint perf counter:
-e tracepoint_subsystem:tracepoint_name:flags
This is intended to be generic although for now it only supports the
r[e[c[o[r[d]]]]] flag:./perf record -e workqueue:workqueue_insertion:record
./perf record -e workqueue:workqueue_insertion:rwill have the same effect: enabling the raw samples record for
the given tracepoint counter.In the future, we may want to support further flags, separated
by commas.Signed-off-by: Frederic Weisbecker
Cc: Peter Zijlstra
Cc: Arnaldo Carvalho de Melo
Cc: Mike Galbraith
LKML-Reference:
Signed-off-by: Ingo Molnar -
Provide weak aliases for hw_perf_counter_setup_online(). This is
used by the BTS patches (for v2.6.32), but it interacts with
fixes so propagate this upstream. (it has no effect as of yet)Also export perf_counter_output() to architecture code.
Cc: Peter Zijlstra
Cc: Paul Mackerras
Cc: Frederic Weisbecker
LKML-Reference:
Signed-off-by: Ingo Molnar -
When /sys/kernel/debug is mounted the list can be imense, so
use the pager like the other tools.Signed-off-by: Arnaldo Carvalho de Melo
Acked-by: Frederic Weisbecker
Cc: Peter Zijlstra
LKML-Reference:
Signed-off-by: Ingo Molnar -
Convert the AP325RXA board code to register devices at
arch_initcall() time instead of device_initcall(). This
fix unbreaks pcf8563 RTC driver support.Signed-off-by: Magnus Damm
Signed-off-by: Paul Mundt
