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Expose media manager mark_blk() to targets, as done for the rest of the
media manager callback functions.
Signed-off-by: Javier González <javier@cnexlabs.com>
Updated description
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Break the loop when rqd is not null to reduce
an unnecessary schedule.
Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
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We accidentally return zero here when ERR_PTR(-ENOMEM) is intended.
Fixes: a07b4970f464 ('nvmet: add a generic NVMe target')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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CONFIG_NVME_TARGET has a correct CONFIG_CONFIGFS_FS dependency, but the
newly added NVME_TARGET_LOOP is missing this, resulting in a link
failure:
drivers/nvme/built-in.o: In function `nvmet_init_configfs':
loop.c:(.init.text+0x2a0): undefined reference to `config_group_init'
loop.c:(.init.text+0x2c0): undefined reference to `config_group_init_type_name'
loop.c:(.init.text+0x318): undefined reference to `configfs_register_subsystem'
drivers/nvme/built-in.o: In function `nvmet_exit_configfs':
loop.c:(.exit.text+0x9c): undefined reference to `configfs_unregister_subsystem'
This adds the same dependency here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 3a85a5de29ea ("nvme-loop: add a NVMe loopback host driver")
Signed-off-by: Jens Axboe <axboe@fb.com>
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When a header file is removed from generic-y (often accompanied by the
addition of an arch specific header), the generated wrapper file will
persist, and in some cases may still take precedence over the new arch
header.
For example commit f1fe2d21f4e1 ("MIPS: Add definitions for extended
context") removed ucontext.h from generic-y in arch/mips/include/asm/,
and added an arch/mips/include/uapi/asm/ucontext.h. The continued use of
the wrapper when reusing a dirty build tree resulted in build failures
in arch/mips/kernel/signal.c:
arch/mips/kernel/signal.c: In function ‘sc_to_extcontext’:
arch/mips/kernel/signal.c:142:12: error: ‘struct ucontext’ has no member named ‘uc_extcontext’
return &uc->uc_extcontext;
^
Fix by detecting and removing wrapper headers in generated header
directories that do not correspond to a filename in generic-y, genhdr-y,
or the newly introduced generated-y.
Reported-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Reported-by: Hauke Mehrtens <hauke@hauke-m.de>
Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-kbuild@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Michal Marek <mmarek@suse.com>
Link: http://lkml.kernel.org/r/1466808144-23209-3-git-send-email-james.hogan@imgtec.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Track generated header files which aren't already in genhdr-y, alongside
generic-y wrappers in the */include/generated/[uapi/]asm/ directories.
Currently only x86 generates extra headers in these directories, for the
purposes of enumerating system calls for different ABIs, and xen
hypercalls.
This will allow the asm-generic wrapper handling code to remove stale
wrappers when files are removed from generic-y, without also removing
these headers which are generated separately.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: Michal Marek <mmarek@suse.com>
Link: http://lkml.kernel.org/r/1466808144-23209-2-git-send-email-james.hogan@imgtec.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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http://git.linaro.org/people/daniel.lezcano/linux into timers/core
Pull the clockevents/clocksource tree from Daniel Lezcano:
- Convert the clocksource-probe init functions to return a value in order to
prepare the consolidation of the drivers using the DT. It is a big patchset
but went through 01.org (kbuild bot), linux next and kernel-ci (continuous
integration) (Daniel Lezcano)
- Fix a bad error handling by returning the right value for cadence_ttc
(Christophe Jaillet)
- Fix typo in the Kconfig for the Samsung pwm (Alexandre Belloni)
- Change functions to static for armada-370-xp and digicolor (Ben Dooks)
- Add support for the rk3399 SoC timer by adding bindings and a slight
change in the base address. Take the opportunity to add the DYNIRQ flag
(Huang Tao)
- Fix endian accessors for the Samsung pwm timer (Matthew Leach)
- Add Oxford Semiconductor RPS Dual Timer driver (Neil Armstrong)
- Add a kernel parameter to swich on/off the event stream feature of the arch
arm timer (Will Deacon)
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Remove MSR_NHM_TURBO_RATIO_LIMIT and MSR_IVT_TURBO_RATIO_LIMIT as
they are duplicate.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Replace MSR_NHM_TURBO_RATIO_LIMIT with MSR_TURBO_RATIO_LIMIT.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Replace MSR_NHM_TURBO_RATIO_LIMIT with MSR_TURBO_RATIO_LIMIT.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This file comes from the uAPI definition header, and
should be auto-generated, to be in sync with Kernel changes.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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This file comes from the uAPI definition header, and
should be auto-generated, to be in sync with Kernel changes.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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This file comes from the uAPI definition header, and
should be auto-generated, to be in sync with Kernel changes.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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This is an auto-generated header. Remove the hardcoded one
and do the right thing here.
NOTE: this is a deprecated API. So, we won't make any
effort to try identifying the meaning of this obscure
API that is used only on a legacy driver.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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This file should be auto-generated from the header files,
and not hardcoded.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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Inability to locate a user mode specified transaction ID should not
lead to a kernel crash. For other than XS_TRANSACTION_START also
don't issue anything to xenbus if the specified ID doesn't match that
of any active transaction.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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The typedef handler should do two things to be generic:
1) parse typedef enums;
2) accept both possible syntaxes:
typedef struct foo { .. } foo_t;
typedef struct { .. } foo_t;
Unfortunately, this is needed to parse some legacy DVB
files, like dvb/audio.h.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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When typedef is used on its multiline format, we need to
also parse enum and struct in the same line.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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Be more formal about the valid symbols that are expected by
the parser, to match what c language expects.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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The commit 30f3a6ab44d8 ("spi: pxa2xx: Add support for both chip selects on
Intel Braswell") introduces a support of chipselects for Intel Braswell SPI
host controller. Though it missed to convert the PCI part of the driver.
Do conversion here which enables both chipselects on Intel Braswell when
enumerated via PCI.
We don't care about num_chipselect value since it is overrided inside core
driver.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
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The dmx.h header has two things that causes the parser to
break while handling enums:
per-header enums and the '{' starts on a new line
Both makes the parser to get lexical marks to be detected
as if they were symbols.
Fix it.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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It seems the commit e5262d0568dc ("spi: spi-pxa2xx: SPI support for Intel Quark
X1000") misses one place to be adapted for Intel Quark, i.e. in reset_sccr1().
Clear all RFT bits when call reset_sccr1() on Intel Quark.
Fixes: e5262d0568dc ("spi: spi-pxa2xx: SPI support for Intel Quark X1000")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
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The original commit adding support for continuous voltage mode didn't
handle the regulator ramp delay properly. It treated the delay as a
fixed delay in uS despite the property being defined as uV / uS. Let's
adjust it. Luckily there appear to be no users of this ramp delay for
PWM regulators (as per grepping through device trees in linuxnext).
Note also that the upper bound of usleep_range probably shouldn't be a
full 1 ms longer than the lower bound since I've seen plenty of hardware
with a ramp rate of ~5000 uS / uV and for small jumps the total delays
are in the tens of uS. 1000 is way too much. We'll try to be dynamic
and use 10%.
NOTE: This commit doesn't add support for regulator-enable-ramp-delay.
That could be done in a future patch when someone has a user of that
featre.
Though this patch is shows as "fixing" a bug, there are no actual known
users of continuous mode PWM regulator w/ ramp delay in mainline and so
this likely won't have any effect on anyone unless they are working
out-of-tree with private patches. For anyone in this state, it is
highly encouraged to also pick Boris Brezillon's WIP patches to get
yourself a reliable and glitch-free regulator.
Fixes: 4773be185a0f ("regulator: pwm-regulator: Add support for continuous-voltage")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
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This documents the binding used by Alexander Shiyan's DT support for
the clps711x SPI controller.
I've left the file name to match the ARM platform port name "clps711x"
for consistency with the other bindings, even though the compatible
string refers to the later ep7309 chip.
Linux no longer supports the old clps711x and ep72xx product lines,
but we still use the name. The entire family is now discontinued
by the manufacturer.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
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This is a complex patch for refactoring CLPS711X SPI driver.
This change adds devicetree support and removes board support.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
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When something is deprecated, highlight it, as we want it
to be clearer to the reader.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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As we had to escape the symbols for the ReST markup to not do
the wrong thing, the logic to discover start/end of strings
are not trivial. Improve the end delimiter detection, in order
to highlight more occurrences of the strings.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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This file is auto-generated with DocBook, from the uapi header.
Do the same with Sphinx.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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When the clock is coming from the cmu it is not required to be
disabled and then re-enabled in order to change the rate.
Besides, some exynos chipsets (e.g. exynos5433) do not deliver
any to the SFR if one from the pclk ("spi" in this case) or sclk
("busclk") is disabled.
Remove the clock disabling/enabling to avoid falling into this
situation.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
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This script parses a header file and converts it into a
parsed-literal block, creating references for ioctls,
defines, typedefs, enums and structs.
It also allow an external file to modify the rules, in
order to fix the expressions.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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The existing optimization for same expiry time in mod_timer() checks whether
the timer expiry time is the same as the new requested expiry time. In the old
timer wheel implementation this does not take the slack batching into account,
neither does the new implementation evaluate whether the new expiry time will
requeue the timer to the same bucket.
To optimize that, we can calculate the resulting bucket and check if the new
expiry time is different from the current expiry time. This calculation
happens outside the base lock held region. If the resulting bucket is the same
we can avoid taking the base lock and requeueing the timer.
If the timer needs to be requeued then we have to check under the base lock
whether the base time has changed between the lockless calculation and taking
the lock. If it has changed we need to recalculate under the lock.
This optimization takes effect for timers which are enqueued into the less
granular wheel levels (1 and above). With a simple test case the functionality
has been verified:
Before After
Match: 5.5% 86.6%
Requeue: 94.5% 13.4%
Recalc: <0.01%
In the non optimized case the timer is requeued in 94.5% of the cases. With
the index optimization in place the requeue rate drops to 13.4%. The case
where the lockless index calculation has to be redone is less than 0.01%.
With a real world test case (networking) we observed the following changes:
Before After
Match: 97.8% 99.7%
Requeue: 2.2% 0.3%
Recalc: <0.001%
That means two percent fewer lock/requeue/unlock operations done in one of
the hot path use cases of timers.
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.778527749@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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For further optimizations we need to seperate index calculation
from queueing. No functional change.
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.691159619@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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With the wheel forwading in place and with the HZ=1000 4ms folding we can
avoid running the softirq at all.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.607650550@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The wheel clock is stale when a CPU goes into a long idle sleep. This has the
side effect that timers which are queued end up in the outer wheel levels.
That results in coarser granularity.
To solve this, we keep track of the idle state and forward the wheel clock
whenever possible.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.512039360@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This was a failed attempt to optimize the timer expiry in idle, which was
disabled and never revisited. Remove the cruft.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.431073782@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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After a NOHZ idle sleep the timer wheel must be forwarded to current jiffies.
There might be expired timers so the current code loops and checks the expired
buckets for timers. This can take quite some time for long NOHZ idle periods.
The pending bitmask in the timer base allows us to do a quick search for the
next expiring timer and therefore a fast forward of the base time which
prevents pointless long lasting loops.
For a 3 seconds idle sleep this reduces the catchup time from ~1ms to 5us.
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.351296290@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Move __run_timers() below __next_timer_interrupt() and next_pending_bucket()
in preparation for __run_timers() NOHZ optimization.
No functional change.
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.271872665@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We now have implicit batching in the timer wheel. The slack API is no longer
used, so remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrew F. Davis <afd@ti.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.189813118@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The current timer wheel has some drawbacks:
1) Cascading:
Cascading can be an unbound operation and is completely pointless in most
cases because the vast majority of the timer wheel timers are canceled or
rearmed before expiration. (They are used as timeout safeguards, not as
real timers to measure time.)
2) No fast lookup of the next expiring timer:
In NOHZ scenarios the first timer soft interrupt after a long NOHZ period
must fast forward the base time to the current value of jiffies. As we
have no way to find the next expiring timer fast, the code loops linearly
and increments the base time one by one and checks for expired timers
in each step. This causes unbound overhead spikes exactly in the moment
when we should wake up as fast as possible.
After a thorough analysis of real world data gathered on laptops,
workstations, webservers and other machines (thanks Chris!) I came to the
conclusion that the current 'classic' timer wheel implementation can be
modified to address the above issues.
The vast majority of timer wheel timers is canceled or rearmed before
expiry. Most of them are timeouts for networking and other I/O tasks. The
nature of timeouts is to catch the exception from normal operation (TCP ack
timed out, disk does not respond, etc.). For these kinds of timeouts the
accuracy of the timeout is not really a concern. Timeouts are very often
approximate worst-case values and in case the timeout fires, we already
waited for a long time and performance is down the drain already.
The few timers which actually expire can be split into two categories:
1) Short expiry times which expect halfways accurate expiry
2) Long term expiry times are inaccurate today already due to the
batching which is done for NOHZ automatically and also via the
set_timer_slack() API.
So for long term expiry timers we can avoid the cascading property and just
leave them in the less granular outer wheels until expiry or
cancelation. Timers which are armed with a timeout larger than the wheel
capacity are no longer cascaded. We expire them with the longest possible
timeout (6+ days). We have not observed such timeouts in our data collection,
but at least we handle them, applying the rule of the least surprise.
To avoid extending the wheel levels for HZ=1000 so we can accomodate the
longest observed timeouts (5 days in the network conntrack code) we reduce the
first level granularity on HZ=1000 to 4ms, which effectively is the same as
the HZ=250 behaviour. From our data analysis there is nothing which relies on
that 1ms granularity and as a side effect we get better batching and timer
locality for the networking code as well.
Contrary to the classic wheel the granularity of the next wheel is not the
capacity of the first wheel. The granularities of the wheels are in the
currently chosen setting 8 times the granularity of the previous wheel.
So for HZ=250 we end up with the following granularity levels:
Level Offset Granularity Range
0 0 4 ms 0 ms - 252 ms
1 64 32 ms 256 ms - 2044 ms (256ms - ~2s)
2 128 256 ms 2048 ms - 16380 ms (~2s - ~16s)
3 192 2048 ms (~2s) 16384 ms - 131068 ms (~16s - ~2m)
4 256 16384 ms (~16s) 131072 ms - 1048572 ms (~2m - ~17m)
5 320 131072 ms (~2m) 1048576 ms - 8388604 ms (~17m - ~2h)
6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h)
7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d)
That's a worst case inaccuracy of 12.5% for the timers which are queued at the
beginning of a level.
So the new wheel concept addresses the old issues:
1) Cascading is avoided completely
2) By keeping the timers in the bucket until expiry/cancelation we can track
the buckets which have timers enqueued in a bucket bitmap and therefore can
look up the next expiring timer very fast and O(1).
A further benefit of the concept is that the slack calculation which is done
on every timer start is no longer necessary because the granularity levels
provide natural batching already.
Our extensive testing with various loads did not show any performance
degradation vs. the current wheel implementation.
This patch does not address the 'fast lookup' issue as we wanted to make sure
that there is no regression introduced by the wheel redesign. The
optimizations are in follow up patches.
This patch contains fixes from Anna-Maria Gleixner and Richard Cochran.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.108621834@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We want to store the array index in the flags space. 256k CPUs should be
enough for a while.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.030144293@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Some of the names in the internal implementation of the timer code
are not longer correct and others are simply too long to type.
Clean it up before we switch the wheel implementation over to
the new scheme.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.948752516@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Required to figure out whether the entry is the only one in the hlist.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.867631372@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We've converted most timeout related syscalls to hrtimers, but
sigtimedwait() did not get this treatment.
Convert it so we get a reasonable accuracy and remove the
user space exposure to the timer wheel properties.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Cyril Hrubis <chrubis@suse.cz>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.787164909@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We switched all users to initialize the timers as pinned and call
mod_timer(). Remove the now unused timer API function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.706205231@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Pinned timers must carry the pinned attribute in the timer structure
itself, so convert the code to the new API.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.617891430@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Pinned timers must carry the pinned attribute in the timer structure
itself, so convert the code to the new API.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.537448301@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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|
Pinned timers must carry the pinned attribute in the timer structure
itself, so convert the code to the new API.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.456452642@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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