25 Oct, 2016
1 commit
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Now that mutex::count and mutex::owner are the same field, we can
allow SPIN_ON_OWNER while DEBUG_MUTEX.Tested-by: Jason Low
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
12 May, 2015
1 commit
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To be consistent with the queued spinlocks which use
CONFIG_QUEUED_SPINLOCKS config parameter, the one for the queued
rwlocks is now renamed to CONFIG_QUEUED_RWLOCKS.Signed-off-by: Waiman Long
Cc: Borislav Petkov
Cc: Douglas Hatch
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Scott J Norton
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/1431367031-36697-1-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar
11 May, 2015
1 commit
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Valentin Rothberg reported that we use CONFIG_QUEUED_SPINLOCKS
in arch/x86/kernel/paravirt_patch_32.c, while the symbol is
called CONFIG_QUEUED_SPINLOCK. (Note the extra 'S')But the typo was natural: the proper English term for such
a generic object would be 'queued spinlocks' - so rename
this and related symbols accordingly to the plural form.Reported-by: Valentin Rothberg
Cc: Douglas Hatch
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Scott J Norton
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
08 May, 2015
3 commits
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This patch adds the necessary Xen specific code to allow Xen to
support the CPU halting and kicking operations needed by the queue
spinlock PV code.Signed-off-by: David Vrabel
Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Boris Ostrovsky
Cc: Borislav Petkov
Cc: Daniel J Blueman
Cc: Douglas Hatch
Cc: H. Peter Anvin
Cc: Konrad Rzeszutek Wilk
Cc: Linus Torvalds
Cc: Oleg Nesterov
Cc: Paolo Bonzini
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Raghavendra K T
Cc: Rik van Riel
Cc: Scott J Norton
Cc: Thomas Gleixner
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-12-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar -
This patch adds the necessary KVM specific code to allow KVM to
support the CPU halting and kicking operations needed by the queue
spinlock PV code.Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Boris Ostrovsky
Cc: Borislav Petkov
Cc: Daniel J Blueman
Cc: David Vrabel
Cc: Douglas Hatch
Cc: H. Peter Anvin
Cc: Konrad Rzeszutek Wilk
Cc: Linus Torvalds
Cc: Oleg Nesterov
Cc: Paolo Bonzini
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Raghavendra K T
Cc: Rik van Riel
Cc: Scott J Norton
Cc: Thomas Gleixner
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-11-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar -
This patch introduces a new generic queued spinlock implementation that
can serve as an alternative to the default ticket spinlock. Compared
with the ticket spinlock, this queued spinlock should be almost as fair
as the ticket spinlock. It has about the same speed in single-thread
and it can be much faster in high contention situations especially when
the spinlock is embedded within the data structure to be protected.Only in light to moderate contention where the average queue depth
is around 1-3 will this queued spinlock be potentially a bit slower
due to the higher slowpath overhead.This queued spinlock is especially suit to NUMA machines with a large
number of cores as the chance of spinlock contention is much higher
in those machines. The cost of contention is also higher because of
slower inter-node memory traffic.Due to the fact that spinlocks are acquired with preemption disabled,
the process will not be migrated to another CPU while it is trying
to get a spinlock. Ignoring interrupt handling, a CPU can only be
contending in one spinlock at any one time. Counting soft IRQ, hard
IRQ and NMI, a CPU can only have a maximum of 4 concurrent lock waiting
activities. By allocating a set of per-cpu queue nodes and used them
to form a waiting queue, we can encode the queue node address into a
much smaller 24-bit size (including CPU number and queue node index)
leaving one byte for the lock.Please note that the queue node is only needed when waiting for the
lock. Once the lock is acquired, the queue node can be released to
be used later.Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Boris Ostrovsky
Cc: Borislav Petkov
Cc: Daniel J Blueman
Cc: David Vrabel
Cc: Douglas Hatch
Cc: H. Peter Anvin
Cc: Konrad Rzeszutek Wilk
Cc: Linus Torvalds
Cc: Oleg Nesterov
Cc: Paolo Bonzini
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Raghavendra K T
Cc: Rik van Riel
Cc: Scott J Norton
Cc: Thomas Gleixner
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-2-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar
14 Jan, 2015
1 commit
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We have two flavors of the MCS spinlock: standard and cancelable (OSQ).
While each one is independent of the other, we currently mix and match
them. This patch:- Moves the OSQ code out of mcs_spinlock.h (which only deals with the traditional
version) into include/linux/osq_lock.h. No unnecessary code is added to the
more global header file, anything locks that make use of OSQ must include
it anyway.- Renames mcs_spinlock.c to osq_lock.c. This file only contains osq code.
- Introduces a CONFIG_LOCK_SPIN_ON_OWNER in order to only build osq_lock
if there is support for it.Signed-off-by: Davidlohr Bueso
Signed-off-by: Peter Zijlstra (Intel)
Cc: Thomas Gleixner
Cc: "Paul E. McKenney"
Cc: Jason Low
Cc: Linus Torvalds
Cc: Mikulas Patocka
Cc: Waiman Long
Link: http://lkml.kernel.org/r/1420573509-24774-5-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar
16 Jul, 2014
2 commits
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Just like with mutexes (CONFIG_MUTEX_SPIN_ON_OWNER),
encapsulate the dependencies for rwsem optimistic spinning.
No logical changes here as it continues to depend on both
SMP and the XADD algorithm variant.Signed-off-by: Davidlohr Bueso
Acked-by: Jason Low
[ Also make it depend on ARCH_SUPPORTS_ATOMIC_RMW. ]
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1405112406-13052-2-git-send-email-davidlohr@hp.com
Cc: aswin@hp.com
Cc: Chris Mason
Cc: Davidlohr Bueso
Cc: Josef Bacik
Cc: Linus Torvalds
Cc: Waiman Long
Signed-off-by: Ingo MolnarSigned-off-by: Ingo Molnar
-
The optimistic spin code assumes regular stores and cmpxchg() play nice;
this is found to not be true for at least: parisc, sparc32, tile32,
metag-lock1, arc-!llsc and hexagon.There is further wreckage, but this in particular seemed easy to
trigger, so blacklist this.Opt in for known good archs.
Signed-off-by: Peter Zijlstra
Reported-by: Mikulas Patocka
Cc: David Miller
Cc: Chris Metcalf
Cc: James Bottomley
Cc: Vineet Gupta
Cc: Jason Low
Cc: Waiman Long
Cc: "James E.J. Bottomley"
Cc: Paul McKenney
Cc: John David Anglin
Cc: James Hogan
Cc: Linus Torvalds
Cc: Davidlohr Bueso
Cc: stable@vger.kernel.org
Cc: Benjamin Herrenschmidt
Cc: Catalin Marinas
Cc: Russell King
Cc: Will Deacon
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/20140606175316.GV13930@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar
06 Jun, 2014
1 commit
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This rwlock uses the arch_spin_lock_t as a waitqueue, and assuming the
arch_spin_lock_t is a fair lock (ticket,mcs etc..) the resulting
rwlock is a fair lock.It fits in the same 8 bytes as the regular rwlock_t by folding the
reader and writer count into a single integer, using the remaining 4
bytes for the arch_spinlock_t.Architectures that can single-copy adress bytes can optimize
queue_write_unlock() with a 0 write to the LSB (the write count).Performance as measured by Davidlohr Bueso (rwlock_t -> qrwlock_t):
+--------------+-------------+---------------+
| Workload | #users | delta |
+--------------+-------------+---------------+
| alltests | > 1400 | -4.83% |
| custom | 0-100,> 100 | +1.43%,-1.57% |
| high_systime | > 1000 | -2.61 |
| shared | all | +0.32 |
+--------------+-------------+---------------+http://www.stgolabs.net/qrwlock-stuff/aim7-results-vs-rwsem_optsin/
Signed-off-by: Waiman Long
[peterz: near complete rewrite]
Signed-off-by: Peter Zijlstra
Cc: Arnd Bergmann
Cc: Linus Torvalds
Cc: "Paul E.McKenney"
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-gac1nnl3wvs2ij87zv2xkdzq@git.kernel.org
Signed-off-by: Ingo Molnar
28 May, 2013
1 commit
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The Kconfig symbols ARCH_INLINE_READ_UNLOCK_IRQ,
ARCH_INLINE_SPIN_UNLOCK_IRQ, and ARCH_INLINE_WRITE_UNLOCK_IRQ were added
in v2.6.33, but have never actually been used. Ingo Molnar spotted that
this is caused by three identical copy/paste erros. Eg, the Kconfig
entry forINLINE_READ_UNLOCK_IRQ
has an (optional) dependency on:
ARCH_INLINE_READ_UNLOCK_BH
were it apparently should depend on:
ARCH_INLINE_READ_UNLOCK_IRQ
instead. Likewise for the Kconfig entries for INLINE_SPIN_UNLOCK_IRQ and
INLINE_WRITE_UNLOCK_IRQ. Fix these three errors.This never really caused any real problems as these symbols are set (or
unset) in a group - but it's worth fixing it nevertheless.Reported-by: Ingo Molnar
Signed-off-by: Paul Bolle
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1368780693.1350.228.camel@x61.thuisdomein
Signed-off-by: Ingo Molnar
13 Sep, 2012
1 commit
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Break out the DEBUG_SPINLOCK dependency (requires moving up
UNINLINE_SPIN_UNLOCK, as this was the only one in that block not
depending on that option).Avoid putting values not selected into the resulting .config -
they are not useful for anything, make the output less legible,
and just consume space: Use "depends on" rather than directly
setting the default from the combined dependency values.Signed-off-by: Jan Beulich
Cc: Linus Torvalds
Cc: Peter Zijlstra
Link: http://lkml.kernel.org/r/504DF2AC020000780009A2DF@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar
23 Mar, 2012
1 commit
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Get rid of INLINE_SPIN_UNLOCK entirely replacing it with
UNINLINE_SPIN_UNLOCK instead of the reverse meaning.Whoever wants to change the default spinlock inlining
behavior and uninline the spinlocks for some weird reason,
such as spinlock debugging, paravirt etc. can now all just
select UNINLINE_SPIN_UNLOCKOriginal discussion at: https://lkml.org/lkml/2012/3/21/357
Suggested-by: Linus Torvalds
Signed-off-by: Raghavendra K T
Cc: Linus Torvalds
Cc: Ralf Baechle
Cc: Chris Metcalf
Cc: Chris Zankel
Cc: linux-mips@linux-mips.org
Link: http://lkml.kernel.org/r/20120322095502.30866.75756.sendpatchset@codeblue
[ tidied up the changelog a bit ]
Signed-off-by: Ingo Molnar
10 Apr, 2011
1 commit
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Signed-off-by: Justin P. Mattock
Acked-by: Steven Rostedt
Acked-by: Heiko Carstens
Signed-off-by: Jiri Kosina
03 Dec, 2009
1 commit
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Introduce CONFIG_MUTEX_SPIN_ON_OWNER so that we can centralize
in a single place the conditions that determine its definition
and use.Signed-off-by: Frederic Weisbecker
Acked-by: Peter Zijlstra
LKML-Reference:
Signed-off-by: Ingo Molnar
Cc: Peter Zijlstra
14 Nov, 2009
1 commit
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commit 892a7c67 (locking: Allow arch-inlined spinlocks) implements the
selection of which lock functions are inlined based on defines in
arch/.../spinlock.h: #define __always_inline__LOCK_FUNCTIONDespite of the name __always_inline__* the lock functions can be built
out of line depending on config options. Also if the arch does not set
some inline defines the generic code might set them; again depending on
config options.This makes it unnecessary hard to figure out when and which lock
functions are inlined. Aside of that it makes it way harder and
messier for -rt to manipulate the lock functions.Convert the inlining decision to CONFIG switches. Each lock function
is inlined depending on CONFIG_INLINE_*. The configs implement the
existing dependencies. The architecture code can select ARCH_INLINE_*
to signal that it wants the corresponding lock function inlined.
ARCH_INLINE_* is necessary as Kconfig ignores "depends on"
restrictions when a config element is selected.No functional change.
Signed-off-by: Thomas Gleixner
LKML-Reference:
Acked-by: Heiko Carstens
Reviewed-by: Ingo Molnar
Acked-by: Peter Zijlstra
