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This reverts commit 1332a90558013ae4242e3dd7934bdcdeafb06c0d.
The original issue was not because of incorrect checking of cpumask for
both new and old tick device. It was incorrectly analysed was due to the
misunderstanding of the comment and misinterpretation of the return value
from tick_check_preferred. The main issue is with the clockevent driver
that sets the cpumask to cpu_all_mask instead of cpu_possible_mask.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1531151136-18297-1-git-send-email-sudeep.holla@arm.com
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For the common cases where 1000 is a multiple of HZ, or HZ is a multiple of
1000, jiffies_to_msecs() never returns zero when passed a non-zero time
period.
However, if HZ > 1000 and not an integer multiple of 1000 (e.g. 1024 or
1200, as used on alpha and DECstation), jiffies_to_msecs() may return zero
for small non-zero time periods. This may break code that relies on
receiving back a non-zero value.
jiffies_to_usecs() does not need such a fix: one jiffy can only be less
than one µs if HZ > 1000000, and such large values of HZ are already
rejected at build time, twice:
- include/linux/jiffies.h does #error if HZ >= 12288,
- kernel/time/time.c has BUILD_BUG_ON(HZ > USEC_PER_SEC).
Broken since forever.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-alpha@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180622143357.7495-1-geert@linux-m68k.org
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Commit b5793b0d92c9 added support for building the nanosleep compat system
call on 32-bit architectures, but missed one change in nanosleep_copyout(),
which would trigger a BUG() as soon as any architecture is switched over to
use it.
Use the proper config symbol to enable the code path.
Fixes: Commit b5793b0d92c9 ("posix-timers: Make compat syscalls depend on CONFIG_COMPAT_32BIT_TIME")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: y2038@lists.linaro.org
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20180618140811.2998503-1-arnd@arndb.de
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The lockdep_assert_irqs_disabled() was a BUG_ON() statement in the
beginning and it was added just before the "spin_lock(siglock)"
statement to ensure this lock was taken with disabled interrupts.
This is no longer the case: the siglock is acquired via
lock_task_sighand() and this function already disables the interrupts.
The lock is also acquired before this "lockdep_assert_irqs_disabled" so
it is best to remove it.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r20180504152548.7166-1-bigeasy@linutronix.de
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Pull power management updates from Rafael Wysocki:
"These include a significant update of the generic power domains
(genpd) and Operating Performance Points (OPP) frameworks, mostly
related to the introduction of power domain performance levels,
cpufreq updates (new driver for Qualcomm Kryo processors, updates of
the existing drivers, some core fixes, schedutil governor
improvements), PCI power management fixes, ACPI workaround for
EC-based wakeup events handling on resume from suspend-to-idle, and
major updates of the turbostat and pm-graph utilities.
Specifics:
- Introduce power domain performance levels into the the generic
power domains (genpd) and Operating Performance Points (OPP)
frameworks (Viresh Kumar, Rajendra Nayak, Dan Carpenter).
- Fix two issues in the runtime PM framework related to the
initialization and removal of devices using device links (Ulf
Hansson).
- Clean up the initialization of drivers for devices in PM domains
(Ulf Hansson, Geert Uytterhoeven).
- Fix a cpufreq core issue related to the policy sysfs interface
causing CPU online to fail for CPUs sharing one cpufreq policy in
some situations (Tao Wang).
- Make it possible to use platform-specific suspend/resume hooks in
the cpufreq-dt driver and make the Armada 37xx DVFS use that
feature (Viresh Kumar, Miquel Raynal).
- Optimize policy transition notifications in cpufreq (Viresh Kumar).
- Improve the iowait boost mechanism in the schedutil cpufreq
governor (Patrick Bellasi).
- Improve the handling of deferred frequency updates in the schedutil
cpufreq governor (Joel Fernandes, Dietmar Eggemann, Rafael Wysocki,
Viresh Kumar).
- Add a new cpufreq driver for Qualcomm Kryo (Ilia Lin).
- Fix and clean up some cpufreq drivers (Colin Ian King, Dmitry
Osipenko, Doug Smythies, Luc Van Oostenryck, Simon Horman, Viresh
Kumar).
- Fix the handling of PCI devices with the DPM_SMART_SUSPEND flag set
and update stale comments in the PCI core PM code (Rafael Wysocki).
- Work around an issue related to the handling of EC-based wakeup
events in the ACPI PM core during resume from suspend-to-idle if
the EC has been put into the low-power mode (Rafael Wysocki).
- Improve the handling of wakeup source objects in the PM core (Doug
Berger, Mahendran Ganesh, Rafael Wysocki).
- Update the driver core to prevent deferred probe from breaking
suspend/resume ordering (Feng Kan).
- Clean up the PM core somewhat (Bjorn Helgaas, Ulf Hansson, Rafael
Wysocki).
- Make the core suspend/resume code and cpufreq support the RT patch
(Sebastian Andrzej Siewior, Thomas Gleixner).
- Consolidate the PM QoS handling in cpuidle governors (Rafael
Wysocki).
- Fix a possible crash in the hibernation core (Tetsuo Handa).
- Update the rockchip-io Adaptive Voltage Scaling (AVS) driver (David
Wu).
- Update the turbostat utility (fixes, cleanups, new CPU IDs, new
command line options, built-in "Low Power Idle" counters support,
new POLL and POLL% columns) and add an entry for it to MAINTAINERS
(Len Brown, Artem Bityutskiy, Chen Yu, Laura Abbott, Matt Turner,
Prarit Bhargava, Srinivas Pandruvada).
- Update the pm-graph to version 5.1 (Todd Brandt).
- Update the intel_pstate_tracer utility (Doug Smythies)"
* tag 'pm-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (128 commits)
tools/power turbostat: update version number
tools/power turbostat: Add Node in output
tools/power turbostat: add node information into turbostat calculations
tools/power turbostat: remove num_ from cpu_topology struct
tools/power turbostat: rename num_cores_per_pkg to num_cores_per_node
tools/power turbostat: track thread ID in cpu_topology
tools/power turbostat: Calculate additional node information for a package
tools/power turbostat: Fix node and siblings lookup data
tools/power turbostat: set max_num_cpus equal to the cpumask length
tools/power turbostat: if --num_iterations, print for specific number of iterations
tools/power turbostat: Add Cannon Lake support
tools/power turbostat: delete duplicate #defines
x86: msr-index.h: Correct SNB_C1/C3_AUTO_UNDEMOTE defines
tools/power turbostat: Correct SNB_C1/C3_AUTO_UNDEMOTE defines
tools/power turbostat: add POLL and POLL% column
tools/power turbostat: Fix --hide Pk%pc10
tools/power turbostat: Build-in "Low Power Idle" counters support
tools/power turbostat: Don't make man pages executable
tools/power turbostat: remove blank lines
tools/power turbostat: a small C-states dump readability immprovement
...
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Pull time/Y2038 updates from Thomas Gleixner:
- Consolidate SySV IPC UAPI headers
- Convert SySV IPC to the new COMPAT_32BIT_TIME mechanism
- Cleanup the core interfaces and standardize on the ktime_get_* naming
convention.
- Convert the X86 platform ops to timespec64
- Remove the ugly temporary timespec64 hack
* 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
x86: Convert x86_platform_ops to timespec64
timekeeping: Add more coarse clocktai/boottime interfaces
timekeeping: Add ktime_get_coarse_with_offset
timekeeping: Standardize on ktime_get_*() naming
timekeeping: Clean up ktime_get_real_ts64
timekeeping: Remove timespec64 hack
y2038: ipc: Redirect ipc(SEMTIMEDOP, ...) to compat_ksys_semtimedop
y2038: ipc: Enable COMPAT_32BIT_TIME
y2038: ipc: Use __kernel_timespec
y2038: ipc: Report long times to user space
y2038: ipc: Use ktime_get_real_seconds consistently
y2038: xtensa: Extend sysvipc data structures
y2038: powerpc: Extend sysvipc data structures
y2038: sparc: Extend sysvipc data structures
y2038: parisc: Extend sysvipc data structures
y2038: mips: Extend sysvipc data structures
y2038: arm64: Extend sysvipc compat data structures
y2038: s390: Remove unneeded ipc uapi header files
y2038: ia64: Remove unneeded ipc uapi header files
y2038: alpha: Remove unneeded ipc uapi header files
...
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Pull timers and timekeeping updates from Thomas Gleixner:
- Core infrastucture work for Y2038 to address the COMPAT interfaces:
+ Add a new Y2038 safe __kernel_timespec and use it in the core
code
+ Introduce config switches which allow to control the various
compat mechanisms
+ Use the new config switch in the posix timer code to control the
32bit compat syscall implementation.
- Prevent bogus selection of CPU local clocksources which causes an
endless reselection loop
- Remove the extra kthread in the clocksource code which has no value
and just adds another level of indirection
- The usual bunch of trivial updates, cleanups and fixlets all over the
place
- More SPDX conversions
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
clocksource/drivers/mxs_timer: Switch to SPDX identifier
clocksource/drivers/timer-imx-tpm: Switch to SPDX identifier
clocksource/drivers/timer-imx-gpt: Switch to SPDX identifier
clocksource/drivers/timer-imx-gpt: Remove outdated file path
clocksource/drivers/arc_timer: Add comments about locking while read GFRC
clocksource/drivers/mips-gic-timer: Add pr_fmt and reword pr_* messages
clocksource/drivers/sprd: Fix Kconfig dependency
clocksource: Move inline keyword to the beginning of function declarations
timer_list: Remove unused function pointer typedef
timers: Adjust a kernel-doc comment
tick: Prefer a lower rating device only if it's CPU local device
clocksource: Remove kthread
time: Change nanosleep to safe __kernel_* types
time: Change types to new y2038 safe __kernel_* types
time: Fix get_timespec64() for y2038 safe compat interfaces
time: Add new y2038 safe __kernel_timespec
posix-timers: Make compat syscalls depend on CONFIG_COMPAT_32BIT_TIME
time: Introduce CONFIG_COMPAT_32BIT_TIME
time: Introduce CONFIG_64BIT_TIME in architectures
compat: Enable compat_get/put_timespec64 always
...
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Pull procfs updates from Al Viro:
"Christoph's proc_create_... cleanups series"
* 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (44 commits)
xfs, proc: hide unused xfs procfs helpers
isdn/gigaset: add back gigaset_procinfo assignment
proc: update SIZEOF_PDE_INLINE_NAME for the new pde fields
tty: replace ->proc_fops with ->proc_show
ide: replace ->proc_fops with ->proc_show
ide: remove ide_driver_proc_write
isdn: replace ->proc_fops with ->proc_show
atm: switch to proc_create_seq_private
atm: simplify procfs code
bluetooth: switch to proc_create_seq_data
netfilter/x_tables: switch to proc_create_seq_private
netfilter/xt_hashlimit: switch to proc_create_{seq,single}_data
neigh: switch to proc_create_seq_data
hostap: switch to proc_create_{seq,single}_data
bonding: switch to proc_create_seq_data
rtc/proc: switch to proc_create_single_data
drbd: switch to proc_create_single
resource: switch to proc_create_seq_data
staging/rtl8192u: simplify procfs code
jfs: simplify procfs code
...
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timekeeping suspend/resume calls read_persistent_clock() which takes
rtc_lock. That results in might sleep warnings because at that point
we run with interrupts disabled.
We cannot convert rtc_lock to a raw spinlock as that would trigger
other might sleep warnings.
As a workaround we disable the might sleep warnings by setting
system_state to SYSTEM_SUSPEND before calling sysdev_suspend() and
restoring it to SYSTEM_RUNNING afer sysdev_resume(). There is no lock
contention because hibernate / suspend to RAM is single-CPU at this
point.
In s2idle's case the system_state is set to SYSTEM_SUSPEND before
timekeeping_suspend() which is invoked by the last CPU. In the resume
case it set back to SYSTEM_RUNNING after timekeeping_resume() which is
invoked by the first CPU in the resume case. The other CPUs will block
on tick_freeze_lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: cover s2idle in tick_freeze() / tick_unfreeze()]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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I have run into a couple of drivers using current_kernel_time()
suffering from the y2038 problem, and they could be converted
to using ktime_t, but don't have interfaces that skip the nanosecond
calculation at the moment.
This introduces ktime_get_coarse_with_offset() as a simpler
variant of ktime_get_with_offset(), and adds wrappers for the
three time domains we support with the existing function.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180427134016.2525989-5-arnd@arndb.de
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The current_kernel_time64, get_monotonic_coarse64, getrawmonotonic64,
get_monotonic_boottime64 and timekeeping_clocktai64 interfaces have
rather inconsistent naming, and they differ in the calling conventions
by passing the output either by reference or as a return value.
Rename them to ktime_get_coarse_real_ts64, ktime_get_coarse_ts64,
ktime_get_raw_ts64, ktime_get_boottime_ts64 and ktime_get_clocktai_ts64
respectively, and provide the interfaces with macros or inline
functions as needed.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180427134016.2525989-4-arnd@arndb.de
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In a move to make ktime_get_*() the preferred driver interface into the
timekeeping code, sanitizes ktime_get_real_ts64() to be a proper exported
symbol rather than an alias for getnstimeofday64().
The internal __getnstimeofday64() is no longer used, so remove that
and merge it into ktime_get_real_ts64().
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180427134016.2525989-3-arnd@arndb.de
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At this point, we have converted most of the kernel to use timespec64
consistently in place of timespec, so it seems it's time to make
timespec64 the native structure and define timespec in terms of that
one on 64-bit architectures.
Starting with gcc-5, the compiler can completely optimize away the
timespec_to_timespec64 and timespec64_to_timespec functions on 64-bit
architectures. With older compilers, we introduce a couple of extra
copies of local variables, but those are easily avoided by using
the timespec64 based interfaces consistently, as we do in most of the
important code paths already.
The main upside of removing the hack is that printing the tv_sec
field of a timespec64 structure can now use the %lld format
string on all architectures without a cast to time64_t. Without
this patch, the field is a 'long' type and would have to be printed
using %ld on 64-bit architectures.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180427134016.2525989-2-arnd@arndb.de
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Merge upstream to pick up changes on which pending patches depend on.
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The inline keyword was not at the beginning of the function declarations.
Fix the following warnings triggered when using W=1:
kernel/time/clocksource.c:456:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]
kernel/time/clocksource.c:457:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180516195943.31924-1-malat@debian.org
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Variant of proc_create_data that directly take a struct seq_operations
argument + a private state size and drastically reduces the boilerplate
code in the callers.
All trivial callers converted over.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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for_each_cpu() unintuitively reports CPU0 as set independent of the actual
cpumask content on UP kernels. This causes an unexpected PIT interrupt
storm on a UP kernel running in an SMP virtual machine on Hyper-V, and as
a result, the virtual machine can suffer from a strange random delay of 1~20
minutes during boot-up, and sometimes it can hang forever.
Protect if by checking whether the cpumask is empty before entering the
for_each_cpu() loop.
[ tglx: Use !IS_ENABLED(CONFIG_SMP) instead of #ifdeffery ]
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poulson <jopoulso@microsoft.com>
Cc: "Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: stable@vger.kernel.org
Cc: Rakib Mullick <rakib.mullick@gmail.com>
Cc: Jork Loeser <Jork.Loeser@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Link: https://lkml.kernel.org/r/KL1P15301MB000678289FE55BA365B3279ABF990@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM
Link: https://lkml.kernel.org/r/KL1P15301MB0006FA63BC22BEB64902EAA0BF930@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM
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Remove the 'printf_fn_t' typedef as it is not used.
Signed-off-by: Chen Lin <chen45464546@163.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: sboyd@kernel.org
Cc: john.stultz@linaro.org
Link: https://lkml.kernel.org/r/1526053649-24229-1-git-send-email-chen45464546@163.com
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Those three warnings can easily solved by using :: to indicate a
code block:
./kernel/time/timer.c:1259: WARNING: Unexpected indentation.
./kernel/time/timer.c:1261: WARNING: Unexpected indentation.
./kernel/time/timer.c:1262: WARNING: Block quote ends without a blank line; unexpected unindent.
While here, align the lines at the block.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Linux Doc Mailing List <linux-doc@vger.kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/f02e6a0ce27f3b5e33415d92d07a40598904b3ee.1525684985.git.mchehab%2Bsamsung@kernel.org
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Checking the equality of cpumask for both new and old tick device doesn't
ensure that it's CPU local device. This will cause issue if a low rating
clockevent tick device is registered first followed by the registration
of higher rating clockevent tick device.
In such case, clockevents_released list will never get emptied as both
the devices get selected as preferred one and we will loop forever in
clockevents_notify_released.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://lkml.kernel.org/r/1525881728-4858-1-git-send-email-sudeep.holla@arm.com
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The clocksource watchdog uses a work to spawn a kthread to run the
watchdog. That is about as silly as it sounds, run the watchdog
directly from the work.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: len.brown@intel.com
Cc: rjw@rjwysocki.net
Cc: diego.viola@gmail.com
Cc: rui.zhang@intel.com
Link: https://lkml.kernel.org/r/20180430100344.713862818@infradead.org
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Pick up urgent fixes to apply dependent cleanup patch
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AFAICS the hotplug code no longer uses this function.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: len.brown@intel.com
Cc: rjw@rjwysocki.net
Cc: diego.viola@gmail.com
Cc: rui.zhang@intel.com
Link: https://lkml.kernel.org/r/20180430100344.656525644@infradead.org
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When a registered clocksource gets marked unstable the watchdog_kthread
will de-rate and re-select the clocksource. Ensure it also de-rates
when getting called on an unregistered clocksource.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: len.brown@intel.com
Cc: rjw@rjwysocki.net
Cc: diego.viola@gmail.com
Cc: rui.zhang@intel.com
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180430100344.594904898@infradead.org
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A number of places relies on list_empty(&cs->wd_list), however the
list_head does not get initialized. Do so upon registration, such that
thereafter it is possible to rely on list_empty() correctly reflecting
the list membership status.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Diego Viola <diego.viola@gmail.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: stable@vger.kernel.org
Cc: len.brown@intel.com
Cc: rjw@rjwysocki.net
Cc: rui.zhang@intel.com
Link: https://lkml.kernel.org/r/20180430100344.472662715@infradead.org
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Because of how the code flips between tsc-early and tsc clocksources
it might need to mark one or both unstable. The current code in
mark_tsc_unstable() only worked because previously it registered the
tsc clocksource once and then never touched it.
Since it now unregisters the tsc-early clocksource, it needs to know
if a clocksource got unregistered and the current cs->mult test
doesn't work for that. Instead use list_empty(&cs->list) to test for
registration.
Furthermore, since clocksource_mark_unstable() needs to place the cs
on the wd_list, it links the cs->list and cs->wd_list serialization.
It must not see a clocsource registered (!empty cs->list) but already
past dequeue_watchdog(). So place {en,de}queue{,_watchdog}() under the
same lock.
Provided cs->list is initialized to empty, this then allows us to
unconditionally use clocksource_mark_unstable(), regardless of the
registration state.
Fixes: aa83c45762a2 ("x86/tsc: Introduce early tsc clocksource")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Diego Viola <diego.viola@gmail.com>
Cc: len.brown@intel.com
Cc: rjw@rjwysocki.net
Cc: diego.viola@gmail.com
Cc: rui.zhang@intel.com
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180502135312.GS12217@hirez.programming.kicks-ass.net
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Revert commits
92af4dcb4e1c ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f4342 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a4047aa6 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e913d ("timekeeping: Remove boot time specific code")
f2d6fdbfd238 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449afdb3 ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320d49d ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")
As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.
As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:
* systemd kills daemons on resume, after >WatchdogSec seconds
of suspending (Genki Sky). [Verified that that's because systemd uses
CLOCK_MONOTONIC and expects it to not include the suspend time.]
* systemd-journald misbehaves after resume:
systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
(Mike Galbraith).
* NetworkManager reports "networking disabled" and networking is broken
after resume 50% of the time (Pavel). [May be because of systemd.]
* MATE desktop dims the display and starts the screensaver right after
system resume (Pavel).
* Full system hang during resume (me). [May be due to systemd or NM or both.]
That happens on debian and open suse systems.
It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.
Reported-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
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Kaike reported that in tests rdma hrtimers occasionaly stopped working. He
did great debugging, which provided enough context to decode the problem.
CPU 3 CPU 2
idle
start sched_timer expires = 712171000000
queue->next = sched_timer
start rdmavt timer. expires = 712172915662
lock(baseof(CPU3))
tick_nohz_stop_tick()
tick = 716767000000 timerqueue_add(tmr)
hrtimer_set_expires(sched_timer, tick);
sched_timer->expires = 716767000000 <---- FAIL
if (tmr->expires < queue->next->expires)
hrtimer_start(sched_timer) queue->next = tmr;
lock(baseof(CPU3))
unlock(baseof(CPU3))
timerqueue_remove()
timerqueue_add()
ts->sched_timer is queued and queue->next is pointing to it, but then
ts->sched_timer.expires is modified.
This not only corrupts the ordering of the timerqueue RB tree, it also
makes CPU2 see the new expiry time of timerqueue->next->expires when
checking whether timerqueue->next needs to be updated. So CPU2 sees that
the rdma timer is earlier than timerqueue->next and sets the rdma timer as
new next.
Depending on whether it had also seen the new time at RB tree enqueue, it
might have queued the rdma timer at the wrong place and then after removing
the sched_timer the RB tree is completely hosed.
The problem was introduced with a commit which tried to solve inconsistency
between the hrtimer in the tick_sched data and the underlying hardware
clockevent. It split out hrtimer_set_expires() to store the new tick time
in both the NOHZ and the NOHZ + HIGHRES case, but missed the fact that in
the NOHZ + HIGHRES case the hrtimer might still be queued.
Use hrtimer_start(timer, tick...) for the NOHZ + HIGHRES case which sets
timer->expires after canceling the timer and move the hrtimer_set_expires()
invocation into the NOHZ only code path which is not affected as it merily
uses the hrtimer as next event storage so code pathes can be shared with
the NOHZ + HIGHRES case.
Fixes: d4af6d933ccf ("nohz: Fix spurious warning when hrtimer and clockevent get out of sync")
Reported-by: "Wan Kaike" <kaike.wan@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Cc: "Marciniszyn Mike" <mike.marciniszyn@intel.com>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: linux-rdma@vger.kernel.org
Cc: "Dalessandro Dennis" <dennis.dalessandro@intel.com>
Cc: "Fleck John" <john.fleck@intel.com>
Cc: stable@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "Weiny Ira" <ira.weiny@intel.com>
Cc: "linux-rdma@vger.kernel.org"
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1804241637390.1679@nanos.tec.linutronix.de
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1804242119210.1597@nanos.tec.linutronix.de
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Change over clock_nanosleep syscalls to use y2038 safe
__kernel_timespec times. This will enable changing over
of these syscalls to use new y2038 safe syscalls when
the architectures define the CONFIG_64BIT_TIME.
Note that nanosleep syscall is deprecated and does not have a
plan for making it y2038 safe. But, the syscall should work as
before on 64 bit machines and on 32 bit machines, the syscall
works correctly until y2038 as before using the existing compat
syscall version. There is no new syscall for supporting 64 bit
time_t on 32 bit architectures.
Cc: linux-api@vger.kernel.org
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
|
|
Change over clock_settime, clock_gettime and clock_getres
syscalls to use __kernel_timespec times. This will enable
changing over of these syscalls to use new y2038 safe syscalls
when the architectures define the CONFIG_64BIT_TIME.
Cc: linux-api@vger.kernel.org
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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get/put_timespec64() interfaces will eventually be used for
conversions between the new y2038 safe struct __kernel_timespec
and struct timespec64.
The new y2038 safe syscalls have a common entry for native
and compat interfaces.
On compat interfaces, the high order bits of nanoseconds
should be zeroed out. This is because the application code
or the libc do not guarantee zeroing of these. If used without
zeroing, kernel might be at risk of using timespec values
incorrectly.
Note that clearing of bits is dependent on CONFIG_64BIT_TIME
for now. This is until COMPAT_USE_64BIT_TIME has been handled
correctly. x86 will be the first architecture that will use the
CONFIG_64BIT_TIME.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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clock_gettime, clock_settime, clock_getres and clock_nanosleep
compat syscalls are also repurposed to provide backward compatibility
to support 32 bit time_t on 32 bit systems.
Note that nanosleep compat syscall will also be treated the same way
as the above syscalls as it shares common handler functions with
clock_nanosleep. But, there is no plan to provide y2038 safe solution
for nanosleep.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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|
These functions are used in the repurposed compat syscalls
to provide backward compatibility for using 32 bit time_t
on 32 bit systems.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Commit a9445e47d897 ("posix-cpu-timers: Make set_process_cpu_timer()
more robust") moved the check into the 'if' statement. Unfortunately,
it did so on the right side of an && which means that it may get short
circuited and never evaluated. This is easily reproduced with:
$ cat loop.c
void main() {
struct rlimit res;
/* set the CPU time limit */
getrlimit(RLIMIT_CPU,&res);
res.rlim_cur = 2;
res.rlim_max = 2;
setrlimit(RLIMIT_CPU,&res);
while (1);
}
Which will hang forever instead of being killed. Fix this by pulling the
evaluation out of the if statement but checking the return value instead.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1568337
Fixes: a9445e47d897 ("posix-cpu-timers: Make set_process_cpu_timer() more robust")
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Cc: "Max R . P . Grossmann" <m@max.pm>
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180417215742.2521-1-labbott@redhat.com
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|
The __current_kernel_time() function based on 'struct timespec' is no
longer recommended for new code, and the only user of this function has
been replaced by commit 6909e29fdefb ("kdb: use __ktime_get_real_seconds
instead of __current_kernel_time").
Remove the obsolete interface.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: sboyd@kernel.org
Cc: broonie@kernel.org
Cc: john.stultz@linaro.org
Link: https://lkml.kernel.org/r/1a9dbea7ee2cda7efe9ed330874075cf17fdbff6.1523596316.git.baolin.wang@linaro.org
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Convert the clockevents driver from old-style printk() to pr_info() and
pr_cont(), to fix split kernel messages like below:
Clockevents: could not switch to one-shot mode:
dummy_timer is not functional.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://lkml.kernel.org/r/1522942018-14471-1-git-send-email-geert%2Brenesas@glider.be
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Pull x86 fixes from Thomas Gleixner:
"A set of fixes and updates for x86:
- Address a swiotlb regression which was caused by the recent DMA
rework and made driver fail because dma_direct_supported() returned
false
- Fix a signedness bug in the APIC ID validation which caused invalid
APIC IDs to be detected as valid thereby bloating the CPU possible
space.
- Fix inconsisten config dependcy/select magic for the MFD_CS5535
driver.
- Fix a corruption of the physical address space bits when encryption
has reduced the address space and late cpuinfo updates overwrite
the reduced bit information with the original value.
- Dominiks syscall rework which consolidates the architecture
specific syscall functions so all syscalls can be wrapped with the
same macros. This allows to switch x86/64 to struct pt_regs based
syscalls. Extend the clearing of user space controlled registers in
the entry patch to the lower registers"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/apic: Fix signedness bug in APIC ID validity checks
x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption
x86/olpc: Fix inconsistent MFD_CS5535 configuration
swiotlb: Use dma_direct_supported() for swiotlb_ops
syscalls/x86: Adapt syscall_wrapper.h to the new syscall stub naming convention
syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()
syscalls/core, syscalls/x86: Clean up compat syscall stub naming convention
syscalls/core, syscalls/x86: Clean up syscall stub naming convention
syscalls/x86: Extend register clearing on syscall entry to lower registers
syscalls/x86: Unconditionally enable 'struct pt_regs' based syscalls on x86_64
syscalls/x86: Use 'struct pt_regs' based syscall calling for IA32_EMULATION and x32
syscalls/core: Prepare CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y for compat syscalls
syscalls/x86: Use 'struct pt_regs' based syscall calling convention for 64-bit syscalls
syscalls/core: Introduce CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y
x86/syscalls: Don't pointlessly reload the system call number
x86/mm: Fix documentation of module mapping range with 4-level paging
x86/cpuid: Switch to 'static const' specifier
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Pull kdb updates from Jason Wessel:
- fix 2032 time access issues and new compiler warnings
- minor regression test cleanup
- formatting fixes for end user use of kdb
* tag 'for_linus-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
kdb: use memmove instead of overlapping memcpy
kdb: use ktime_get_mono_fast_ns() instead of ktime_get_ts()
kdb: bl: don't use tab character in output
kdb: drop newline in unknown command output
kdb: make "mdr" command repeat
kdb: use __ktime_get_real_seconds instead of __current_kernel_time
misc: kgdbts: Display progress of asynchronous tests
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* pm-cpuidle:
tick-sched: avoid a maybe-uninitialized warning
cpuidle: Add definition of residency to sysfs documentation
time: hrtimer: Use timerqueue_iterate_next() to get to the next timer
nohz: Avoid duplication of code related to got_idle_tick
nohz: Gather tick_sched booleans under a common flag field
cpuidle: menu: Avoid selecting shallow states with stopped tick
cpuidle: menu: Refine idle state selection for running tick
sched: idle: Select idle state before stopping the tick
time: hrtimer: Introduce hrtimer_next_event_without()
time: tick-sched: Split tick_nohz_stop_sched_tick()
cpuidle: Return nohz hint from cpuidle_select()
jiffies: Introduce USER_TICK_USEC and redefine TICK_USEC
sched: idle: Do not stop the tick before cpuidle_idle_call()
sched: idle: Do not stop the tick upfront in the idle loop
time: tick-sched: Reorganize idle tick management code
* pm-qos:
PM / QoS: mark expected switch fall-throughs
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The use of bitfields seems to confuse gcc, leading to a false-positive
warning in all compiler versions:
kernel/time/tick-sched.c: In function 'tick_nohz_idle_exit':
kernel/time/tick-sched.c:538:2: error: 'now' may be used uninitialized in this function [-Werror=maybe-uninitialized]
This introduces a temporary variable to track the flags so gcc
doesn't have to evaluate twice, eliminating the code path that
leads to the warning.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85301
Fixes: 1cae544d42d2 ("nohz: Gather tick_sched booleans under a common flag field")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Use timerqueue_iterate_next() to get to the next timer in
__hrtimer_next_event_base() without browsing the timerqueue
details diredctly.
No intentional changes in functionality.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
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Move the code setting ts->got_idle_tick into tick_sched_do_timer() to
avoid code duplication.
No intentional changes in functionality.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
|
|
Optimize the space and leave plenty of room for further flags.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
[ rjw: Do not use __this_cpu_read() to access tick_stopped and add
got_idle_tick to avoid overloading inidle ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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If the tick isn't stopped, the target residency of the state selected
by the menu governor may be greater than the actual time to the next
tick and that means lost energy.
To avoid that, make tick_nohz_get_sleep_length() return the current
time to the next event (before stopping the tick) in addition to the
estimated one via an extra pointer argument and make menu_select()
use that value to refine the state selection when necessary.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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In order to address the issue with short idle duration predictions
by the idle governor after the scheduler tick has been stopped,
reorder the code in cpuidle_idle_call() so that the governor idle
state selection runs before tick_nohz_idle_go_idle() and use the
"nohz" hint returned by cpuidle_select() to decide whether or not
to stop the tick.
This isn't straightforward, because menu_select() invokes
tick_nohz_get_sleep_length() to get the time to the next timer
event and the number returned by the latter comes from
__tick_nohz_idle_stop_tick(). Fortunately, however, it is possible
to compute that number without actually stopping the tick and with
the help of the existing code.
Namely, tick_nohz_get_sleep_length() can be made call
tick_nohz_next_event(), introduced earlier, to get the time to the
next non-highres timer event. If that happens, tick_nohz_next_event()
need not be called by __tick_nohz_idle_stop_tick() again.
If it turns out that the scheduler tick cannot be stopped going
forward or the next timer event is too close for the tick to be
stopped, tick_nohz_get_sleep_length() can simply return the time to
the next event currently programmed into the corresponding clock
event device.
In addition to knowing the return value of tick_nohz_next_event(),
however, tick_nohz_get_sleep_length() needs to know the time to the
next highres timer event, but with the scheduler tick timer excluded,
which can be computed with the help of hrtimer_get_next_event().
That minimum of that number and the tick_nohz_next_event() return
value is the total time to the next timer event with the assumption
that the tick will be stopped. It can be returned to the idle
governor which can use it for predicting idle duration (under the
assumption that the tick will be stopped) and deciding whether or
not it makes sense to stop the tick before putting the CPU into the
selected idle state.
With the above, the sleep_length field in struct tick_sched is not
necessary any more, so drop it.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=199227
Reported-by: Doug Smythies <dsmythies@telus.net>
Reported-by: Thomas Ilsche <thomas.ilsche@tu-dresden.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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The next set of changes will need to compute the time to the next
hrtimer event over all hrtimers except for the scheduler tick one.
To that end introduce a new helper function,
hrtimer_next_event_without(), for computing the time until the next
hrtimer event over all timers except for one and modify the underlying
code in __hrtimer_next_event_base() to prepare it for being called by
that new function.
No intentional changes in functionality.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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In order to address the issue with short idle duration predictions
by the idle governor after the scheduler tick has been stopped, split
tick_nohz_stop_sched_tick() into two separate routines, one computing
the time to the next timer event and the other simply stopping the
tick when the time to the next timer event is known.
Prepare these two routines to be called separately, as one of them
will be called by the idle governor in the cpuidle_select() code
path after subsequent changes.
Update the former callers of tick_nohz_stop_sched_tick() to use
the new routines, tick_nohz_next_event() and tick_nohz_stop_tick(),
instead of it and move the updates of the sleep_length field in
struct tick_sched into __tick_nohz_idle_stop_tick() as it doesn't
need to be updated anywhere else.
There should be no intentional visible changes in functionality
resulting from this change.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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Add a new pointer argument to cpuidle_select() and to the ->select
cpuidle governor callback to allow a boolean value indicating
whether or not the tick should be stopped before entering the
selected state to be returned from there.
Make the ladder governor ignore that pointer (to preserve its
current behavior) and make the menu governor return 'false" through
it if:
(1) the idle exit latency is constrained at 0, or
(2) the selected state is a polling one, or
(3) the expected idle period duration is within the tick period
range.
In addition to that, the correction factor computations in the menu
governor need to take the possibility that the tick may not be
stopped into account to avoid artificially small correction factor
values. To that end, add a mechanism to record tick wakeups, as
suggested by Peter Zijlstra, and use it to modify the menu_update()
behavior when tick wakeup occurs. Namely, if the CPU is woken up by
the tick and the return value of tick_nohz_get_sleep_length() is not
within the tick boundary, the predicted idle duration is likely too
short, so make menu_update() try to compensate for that by updating
the governor statistics as though the CPU was idle for a long time.
Since the value returned through the new argument pointer of
cpuidle_select() is not used by its caller yet, this change by
itself is not expected to alter the functionality of the code.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Since the subsequent changes will need a TICK_USEC definition
analogous to TICK_NSEC, rename the existing TICK_USEC as
USER_TICK_USEC, update its users and redefine TICK_USEC
accordingly.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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|
Push the decision whether or not to stop the tick somewhat deeper
into the idle loop.
Stopping the tick upfront leads to unpleasant outcomes in case the
idle governor doesn't agree with the nohz code on the duration of the
upcoming idle period. Specifically, if the tick has been stopped and
the idle governor predicts short idle, the situation is bad regardless
of whether or not the prediction is accurate. If it is accurate, the
tick has been stopped unnecessarily which means excessive overhead.
If it is not accurate, the CPU is likely to spend too much time in
the (shallow, because short idle has been predicted) idle state
selected by the governor [1].
As the first step towards addressing this problem, change the code
to make the tick stopping decision inside of the loop in do_idle().
In particular, do not stop the tick in the cpu_idle_poll() code path.
Also don't do that in tick_nohz_irq_exit() which doesn't really have
enough information on whether or not to stop the tick.
Link: https://marc.info/?l=linux-pm&m=150116085925208&w=2 # [1]
Link: https://tu-dresden.de/zih/forschung/ressourcen/dateien/projekte/haec/powernightmares.pdf
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Sudeep Holla
Geert Uytterhoeven
Arnd Bergmann
Sebastian Andrzej Siewior
Linus Torvalds
Thomas Gleixner
Mathieu Malaterre
Christoph Hellwig
Dexuan Cui
Chen Lin
Mauro Carvalho Chehab
Peter Zijlstra
Deepa Dinamani
Laura Abbott
Baolin Wang
Geert Uytterhoeven
Rafael J. Wysocki
Frederic Weisbecker