Eric Lee / smarc-fsl-linux-kernel

13 Jun, 2009

1 commit

14 Apr, 2009

1 commit

  • 6fd9b3a40   rcu: Update RCU tracing documentation for __rcu_pending ... Browse Code »

    This patch updates the RCU documentation to reflect the changes in
    tracing made in the previous patch in the set.

    Located-by: Anton Blanchard
    Tested-by: Anton Blanchard
    Signed-off-by: Paul E. McKenney
    Cc: anton@samba.org
    Cc: akpm@linux-foundation.org
    Cc: dipankar@in.ibm.com
    Cc: manfred@colorfullife.com
    Cc: cl@linux-foundation.org
    Cc: josht@linux.vnet.ibm.com
    Cc: schamp@sgi.com
    Cc: niv@us.ibm.com
    Cc: dvhltc@us.ibm.com
    Cc: ego@in.ibm.com
    Cc: laijs@cn.fujitsu.com
    Cc: rostedt@goodmis.org
    Cc: peterz@infradead.org
    Cc: penberg@cs.helsinki.fi
    Cc: andi@firstfloor.org
    Cc: "Paul E. McKenney"
    LKML-Reference:
    Signed-off-by: Ingo Molnar

    Paul E. McKenney
     

02 Apr, 2009

3 commits

11 Mar, 2009

1 commit

  • 0612ea00a   rcu: documentation 1Q09 update ... Browse Code »

    Update the RCU documentation to call out the need for callers of
    primitives like call_rcu() and synchronize_rcu() to prevent subsequent RCU
    readers from hazard.

    Signed-off-by: Paul E. McKenney
    Cc: Ingo Molnar
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Paul E. McKenney
     

09 Jan, 2009

1 commit

31 Dec, 2008

1 commit

  • 5f34fe1cf   Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip ... Browse Code »

    * 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (63 commits)
    stacktrace: provide save_stack_trace_tsk() weak alias
    rcu: provide RCU options on non-preempt architectures too
    printk: fix discarding message when recursion_bug
    futex: clean up futex_(un)lock_pi fault handling
    "Tree RCU": scalable classic RCU implementation
    futex: rename field in futex_q to clarify single waiter semantics
    x86/swiotlb: add default swiotlb_arch_range_needs_mapping
    x86/swiotlb: add default physbus conversion
    x86: unify pci iommu setup and allow swiotlb to compile for 32 bit
    x86: add swiotlb allocation functions
    swiotlb: consolidate swiotlb info message printing
    swiotlb: support bouncing of HighMem pages
    swiotlb: factor out copy to/from device
    swiotlb: add arch hook to force mapping
    swiotlb: allow architectures to override physbusphys conversions
    swiotlb: add comment where we handle the overflow of a dma mask on 32 bit
    rcu: fix rcutorture behavior during reboot
    resources: skip sanity check of busy resources
    swiotlb: move some definitions to header
    swiotlb: allow architectures to override swiotlb pool allocation
    ...

    Fix up trivial conflicts in
    arch/x86/kernel/Makefile
    arch/x86/mm/init_32.c
    include/linux/hardirq.h
    as per Ingo's suggestions.

    Linus Torvalds
     

19 Dec, 2008

1 commit

  • 64db4cfff   "Tree RCU": scalable classic RCU implementation ... Browse Code »

    This patch fixes a long-standing performance bug in classic RCU that
    results in massive internal-to-RCU lock contention on systems with
    more than a few hundred CPUs. Although this patch creates a separate
    flavor of RCU for ease of review and patch maintenance, it is intended
    to replace classic RCU.

    This patch still handles stress better than does mainline, so I am still
    calling it ready for inclusion. This patch is against the -tip tree.
    Nevertheless, experience on an actual 1000+ CPU machine would still be
    most welcome.

    Most of the changes noted below were found while creating an rcutiny
    (which should permit ejecting the current rcuclassic) and while doing
    detailed line-by-line documentation.

    Updates from v9 (http://lkml.org/lkml/2008/12/2/334):

    o Fixes from remainder of line-by-line code walkthrough,
    including comment spelling, initialization, undesirable
    narrowing due to type conversion, removing redundant memory
    barriers, removing redundant local-variable initialization,
    and removing redundant local variables.

    I do not believe that any of these fixes address the CPU-hotplug
    issues that Andi Kleen was seeing, but please do give it a whirl
    in case the machine is smarter than I am.

    A writeup from the walkthrough may be found at the following
    URL, in case you are suffering from terminal insomnia or
    masochism:

    http://www.kernel.org/pub/linux/kernel/people/paulmck/tmp/rcutree-walkthrough.2008.12.16a.pdf

    o Made rcutree tracing use seq_file, as suggested some time
    ago by Lai Jiangshan.

    o Added a .csv variant of the rcudata debugfs trace file, to allow
    people having thousands of CPUs to drop the data into
    a spreadsheet. Tested with oocalc and gnumeric. Updated
    documentation to suit.

    Updates from v8 (http://lkml.org/lkml/2008/11/15/139):

    o Fix a theoretical race between grace-period initialization and
    force_quiescent_state() that could occur if more than three
    jiffies were required to carry out the grace-period
    initialization. Which it might, if you had enough CPUs.

    o Apply Ingo's printk-standardization patch.

    o Substitute local variables for repeated accesses to global
    variables.

    o Fix comment misspellings and redundant (but harmless) increments
    of ->n_rcu_pending (this latter after having explicitly added it).

    o Apply checkpatch fixes.

    Updates from v7 (http://lkml.org/lkml/2008/10/10/291):

    o Fixed a number of problems noted by Gautham Shenoy, including
    the cpu-stall-detection bug that he was having difficulty
    convincing me was real. ;-)

    o Changed cpu-stall detection to wait for ten seconds rather than
    three in order to reduce false positive, as suggested by Ingo
    Molnar.

    o Produced a design document (http://lwn.net/Articles/305782/).
    The act of writing this document uncovered a number of both
    theoretical and "here and now" bugs as noted below.

    o Fix dynticks_nesting accounting confusion, simplify WARN_ON()
    condition, fix kerneldoc comments, and add memory barriers
    in dynticks interface functions.

    o Add more data to tracing.

    o Remove unused "rcu_barrier" field from rcu_data structure.

    o Count calls to rcu_pending() from scheduling-clock interrupt
    to use as a surrogate timebase should jiffies stop counting.

    o Fix a theoretical race between force_quiescent_state() and
    grace-period initialization. Yes, initialization does have to
    go on for some jiffies for this race to occur, but given enough
    CPUs...

    Updates from v6 (http://lkml.org/lkml/2008/9/23/448):

    o Fix a number of checkpatch.pl complaints.

    o Apply review comments from Ingo Molnar and Lai Jiangshan
    on the stall-detection code.

    o Fix several bugs in !CONFIG_SMP builds.

    o Fix a misspelled config-parameter name so that RCU now announces
    at boot time if stall detection is configured.

    o Run tests on numerous combinations of configurations parameters,
    which after the fixes above, now build and run correctly.

    Updates from v5 (http://lkml.org/lkml/2008/9/15/92, bad subject line):

    o Fix a compiler error in the !CONFIG_FANOUT_EXACT case (blew a
    changeset some time ago, and finally got around to retesting
    this option).

    o Fix some tracing bugs in rcupreempt that caused incorrect
    totals to be printed.

    o I now test with a more brutal random-selection online/offline
    script (attached). Probably more brutal than it needs to be
    on the people reading it as well, but so it goes.

    o A number of optimizations and usability improvements:

    o Make rcu_pending() ignore the grace-period timeout when
    there is no grace period in progress.

    o Make force_quiescent_state() avoid going for a global
    lock in the case where there is no grace period in
    progress.

    o Rearrange struct fields to improve struct layout.

    o Make call_rcu() initiate a grace period if RCU was
    idle, rather than waiting for the next scheduling
    clock interrupt.

    o Invoke rcu_irq_enter() and rcu_irq_exit() only when
    idle, as suggested by Andi Kleen. I still don't
    completely trust this change, and might back it out.

    o Make CONFIG_RCU_TRACE be the single config variable
    manipulated for all forms of RCU, instead of the prior
    confusion.

    o Document tracing files and formats for both rcupreempt
    and rcutree.

    Updates from v4 for those missing v5 given its bad subject line:

    o Separated dynticks interface so that NMIs and irqs call separate
    functions, greatly simplifying it. In particular, this code
    no longer requires a proof of correctness. ;-)

    o Separated dynticks state out into its own per-CPU structure,
    avoiding the duplicated accounting.

    o The case where a dynticks-idle CPU runs an irq handler that
    invokes call_rcu() is now correctly handled, forcing that CPU
    out of dynticks-idle mode.

    o Review comments have been applied (thank you all!!!).
    For but one example, fixed the dynticks-ordering issue that
    Manfred pointed out, saving me much debugging. ;-)

    o Adjusted rcuclassic and rcupreempt to handle dynticks changes.

    Attached is an updated patch to Classic RCU that applies a hierarchy,
    greatly reducing the contention on the top-level lock for large machines.
    This passes 10-hour concurrent rcutorture and online-offline testing on
    128-CPU ppc64 without dynticks enabled, and exposes some timekeeping
    bugs in presence of dynticks (exciting working on a system where
    "sleep 1" hangs until interrupted...), which were fixed in the
    2.6.27 kernel. It is getting more reliable than mainline by some
    measures, so the next version will be against -tip for inclusion.
    See also Manfred Spraul's recent patches (or his earlier work from
    2004 at http://marc.info/?l=linux-kernel&m=108546384711797&w=2).
    We will converge onto a common patch in the fullness of time, but are
    currently exploring different regions of the design space. That said,
    I have already gratefully stolen quite a few of Manfred's ideas.

    This patch provides CONFIG_RCU_FANOUT, which controls the bushiness
    of the RCU hierarchy. Defaults to 32 on 32-bit machines and 64 on
    64-bit machines. If CONFIG_NR_CPUS is less than CONFIG_RCU_FANOUT,
    there is no hierarchy. By default, the RCU initialization code will
    adjust CONFIG_RCU_FANOUT to balance the hierarchy, so strongly NUMA
    architectures may choose to set CONFIG_RCU_FANOUT_EXACT to disable
    this balancing, allowing the hierarchy to be exactly aligned to the
    underlying hardware. Up to two levels of hierarchy are permitted
    (in addition to the root node), allowing up to 16,384 CPUs on 32-bit
    systems and up to 262,144 CPUs on 64-bit systems. I just know that I
    am going to regret saying this, but this seems more than sufficient
    for the foreseeable future. (Some architectures might wish to set
    CONFIG_RCU_FANOUT=4, which would limit such architectures to 64 CPUs.
    If this becomes a real problem, additional levels can be added, but I
    doubt that it will make a significant difference on real hardware.)

    In the common case, a given CPU will manipulate its private rcu_data
    structure and the rcu_node structure that it shares with its immediate
    neighbors. This can reduce both lock and memory contention by multiple
    orders of magnitude, which should eliminate the need for the strange
    manipulations that are reported to be required when running Linux on
    very large systems.

    Some shortcomings:

    o More bugs will probably surface as a result of an ongoing
    line-by-line code inspection.

    Patches will be provided as required.

    o There are probably hangs, rcutorture failures, &c. Seems
    quite stable on a 128-CPU machine, but that is kind of small
    compared to 4096 CPUs. However, seems to do better than
    mainline.

    Patches will be provided as required.

    o The memory footprint of this version is several KB larger
    than rcuclassic.

    A separate UP-only rcutiny patch will be provided, which will
    reduce the memory footprint significantly, even compared
    to the old rcuclassic. One such patch passes light testing,
    and has a memory footprint smaller even than rcuclassic.
    Initial reaction from various embedded guys was "it is not
    worth it", so am putting it aside.

    Credits:

    o Manfred Spraul for ideas, review comments, and bugs spotted,
    as well as some good friendly competition. ;-)

    o Josh Triplett, Ingo Molnar, Peter Zijlstra, Mathieu Desnoyers,
    Lai Jiangshan, Andi Kleen, Andy Whitcroft, and Andrew Morton
    for reviews and comments.

    o Thomas Gleixner for much-needed help with some timer issues
    (see patches below).

    o Jon M. Tollefson, Tim Pepper, Andrew Theurer, Jose R. Santos,
    Andy Whitcroft, Darrick Wong, Nishanth Aravamudan, Anton
    Blanchard, Dave Kleikamp, and Nathan Lynch for keeping machines
    alive despite my heavy abuse^Wtesting.

    Signed-off-by: Paul E. McKenney
    Signed-off-by: Ingo Molnar

    Paul E. McKenney
     

04 Dec, 2008

1 commit

17 Nov, 2008

1 commit

10 Sep, 2008

1 commit

15 Aug, 2008

1 commit

26 Jun, 2008

1 commit

  • 0729fbf3b   rcu: make rcutorture even more vicious: invoke RCU readers from irq handlers (timers) ... Browse Code »

    This patch allows torturing RCU from irq handlers (timers, in this case).
    A new module parameter irqreader enables such additional torturing,
    and is enabled by default. Variants of RCU that do not tolerate readers
    being called from irq handlers (e.g., SRCU) ignore irqreader.

    Signed-off-by: Paul E. McKenney
    Cc: josh@freedesktop.org
    Cc: dvhltc@us.ibm.com
    Cc: niv@us.ibm.com
    Cc: dino@in.ibm.com
    Cc: akpm@linux-foundation.org
    Cc: torvalds@linux-foundation.org
    Cc: vegard.nossum@gmail.com
    Cc: adobriyan@gmail.com
    Cc: oleg@tv-sign.ru
    Cc: bunk@kernel.org
    Cc: rjw@sisk.pl
    Signed-off-by: Ingo Molnar

    Paul E. McKenney
     

19 Jun, 2008

1 commit

  • 31a72bce0   rcu: make rcutorture more vicious: reinstate boot-time testing ... Browse Code »

    This patch re-institutes the ability to build rcutorture directly into
    the Linux kernel. The reason that this capability was removed was that
    this could result in your kernel being pretty much useless, as rcutorture
    would be running starting from early boot. This problem has been avoided
    by (1) making rcutorture run only three seconds of every six by default,
    (2) adding a CONFIG_RCU_TORTURE_TEST_RUNNABLE that permits rcutorture
    to be quiesced at boot time, and (3) adding a sysctl in /proc named
    /proc/sys/kernel/rcutorture_runnable that permits rcutorture to be
    quiesced and unquiesced when built into the kernel.

    Please note that this /proc file is -not- available when rcutorture
    is built as a module. Please also note that to get the earlier
    take-no-prisoners behavior, you must use the boot command line to set
    rcutorture's "stutter" parameter to zero.

    The rcutorture quiescing mechanism is currently quite crude: loops
    in each rcutorture process that poll a global variable once per tick.
    Suggestions for improvement are welcome. The default action will
    be to reduce the polling rate to a few times per second.

    Signed-off-by: Paul E. McKenney
    Suggested-by: Ingo Molnar
    Signed-off-by: Ingo Molnar

    Paul E. McKenney
     

18 Jun, 2008

1 commit

  • d120f65f3   rcu: make rcutorture more vicious: add stutter feature ... Browse Code »

    This patch takes a step towards making rcutorture more brutal by allowing
    the test to be automatically periodically paused, with the default being
    to run the test for five seconds then pause for five seconds and repeat.
    This behavior can be controlled using a new "stutter" module parameter, so
    that "stutter=0" gives the old default behavior of running continuously.

    Starting and stopping rcutorture more heavily stresses RCU's interaction
    with the scheduler, as well as exercising more paths through the
    grace-period detection code.

    Note that the default to "shuffle_interval" has also been adjusted from
    5 seconds to 3 seconds to provide varying overlap with the "stutter"
    interval.

    I am still unable to provoke the failures that Alexey has been seeing,
    even with this patch, but will be doing a few additional things to beef
    up rcutorture.

    Suggested-by: Ingo Molnar
    Signed-off-by: Paul E. McKenney
    Signed-off-by: Ingo Molnar

    Paul E. McKenney
     

19 May, 2008

1 commit

14 Feb, 2008

1 commit

26 Jan, 2008

1 commit

17 Oct, 2007

1 commit

17 Jul, 2007

1 commit

04 Oct, 2006

8 commits

  • 4b6c2cca6   [PATCH] rcu: add sched torture type to rcutorture ... Browse Code »

    Implement torture testing for the "sched" variant of RCU, which uses
    preempt_disable, preempt_enable, and synchronize_sched.

    Signed-off-by: Josh Triplett
    Acked-by: Paul E. McKenney
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Josh Triplett
     
  • 11a147013   [PATCH] rcu: add rcu_bh_sync torture type to rcutorture ... Browse Code »

    Use the newly-generic synchronous deferred free function to implement torture
    testing for rcu_bh using synchronize_rcu_bh rather than the asynchronous
    call_rcu_bh.

    Signed-off-by: Josh Triplett
    Acked-by: Paul E. McKenney
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Josh Triplett
     
  • 20d2e4283   [PATCH] rcu: add rcu_sync torture type to rcutorture ... Browse Code »

    Use the newly-generic synchronous deferred free function to implement torture
    testing for RCU using synchronize_rcu rather than the asynchronous call_rcu.

    Signed-off-by: Josh Triplett
    Acked-by: Paul E. McKenney
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Josh Triplett
     
  • b772e1dd4   [PATCH] RCU: add fake writers to rcutorture ... Browse Code »

    rcutorture currently has one writer and an arbitrary number of readers. To
    better exercise some of the code paths in RCU implementations, add fake
    writer threads which call the synchronize function for the RCU variant in a
    loop, with a delay between calls to arrange for different numbers of
    writers running in parallel.

    [bunk@stusta.de: cleanup]
    Acked-by: Paul McKenney
    Cc: Dipkanar Sarma
    Signed-off-by: Josh Triplett
    Signed-off-by: Adrian Bunk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Josh Triplett
     
  • b2896d2e7   [PATCH] srcu-3: add SRCU operations to rcutorture ... Browse Code »

    Adds SRCU operations to rcutorture and updates rcutorture documentation.
    Also increases the stress imposed by the rcutorture test.

    [bunk@stusta.de: make needlessly global code static]
    Signed-off-by: Paul E. McKenney
    Cc: Paul E. McKenney
    Signed-off-by: Adrian Bunk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Paul E. McKenney
     
  • 621934ee7   [PATCH] srcu-3: RCU variant permitting read-side blocking ... Browse Code »

    Updated patch adding a variant of RCU that permits sleeping in read-side
    critical sections. SRCU is as follows:

    o Each use of SRCU creates its own srcu_struct, and each
    srcu_struct has its own set of grace periods. This is
    critical, as it prevents one subsystem with a blocking
    reader from holding up SRCU grace periods for other
    subsystems.

    o The SRCU primitives (srcu_read_lock(), srcu_read_unlock(),
    and synchronize_srcu()) all take a pointer to a srcu_struct.

    o The SRCU primitives must be called from process context.

    o srcu_read_lock() returns an int that must be passed to
    the matching srcu_read_unlock(). Realtime RCU avoids the
    need for this by storing the state in the task struct,
    but SRCU needs to allow a given code path to pass through
    multiple SRCU domains -- storing state in the task struct
    would therefore require either arbitrary space in the
    task struct or arbitrary limits on SRCU nesting. So I
    kicked the state-storage problem up to the caller.

    Of course, it is not permitted to call synchronize_srcu()
    while in an SRCU read-side critical section.

    o There is no call_srcu(). It would not be hard to implement
    one, but it seems like too easy a way to OOM the system.
    (Hey, we have enough trouble with call_rcu(), which does
    -not- permit readers to sleep!!!) So, if you want it,
    please tell me why...

    [josht@us.ibm.com: sparse notation]
    Signed-off-by: Paul E. McKenney
    Signed-off-by: Josh Triplett
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Paul E. McKenney
     
  • 670e9f34e   Documentation: remove duplicated words ... Browse Code »

    Remove many duplicated words under Documentation/ and do other small
    cleanups.

    Examples:
    "and and" --> "and"
    "in in" --> "in"
    "the the" --> "the"
    "the the" --> "to the"
    ...

    Signed-off-by: Paolo Ornati
    Signed-off-by: Adrian Bunk

    Paolo Ornati
     
  • 53cb47268   Fix typos in Documentation/: 'S' ... Browse Code »

    This patch fixes typos in various Documentation txts. The patch addresses
    some words starting with the letter 'S'.

    Signed-off-by: Matt LaPlante
    Acked-by: Alan Cox
    Acked-by: Randy Dunlap
    Signed-off-by: Adrian Bunk

    Matt LaPlante
     

11 Jul, 2006

1 commit

28 Jun, 2006

2 commits

26 Jun, 2006

1 commit

  • 165d6c78e   [PATCH] RCU documentation: self-limiting updates and call_rcu() ... Browse Code »

    An update to the RCU documentation calling out the
    self-limiting-update-rate advantages of synchronize_rcu(), and describing
    how to use call_rcu() in a way that results in self-limiting updates.
    Self-limiting updates are important to avoiding RCU-induced OOM in face of
    denial-of-service attacks.

    Signed-off-by: Paul E. McKenney
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Paul E. McKenney
     

23 Jun, 2006

1 commit

29 Mar, 2006

1 commit

25 Mar, 2006

1 commit

02 Feb, 2006

1 commit

09 Jan, 2006

1 commit

07 Nov, 2005

1 commit

31 Oct, 2005

1 commit

  • a241ec65a   [PATCH] RCU torture-testing kernel module ... Browse Code »

    This patch is a rewrite of the one submitted on October 1st, using modules
    (http://marc.theaimsgroup.com/?l=linux-kernel&m=112819093522998&w=2).

    This rewrite adds a tristate CONFIG_RCU_TORTURE_TEST, which enables an
    intense torture test of the RCU infratructure. This is needed due to the
    continued changes to the RCU infrastructure to accommodate dynamic ticks,
    CPU hotplug, realtime, and so on. Most of the code is in a separate file
    that is compiled only if the CONFIG variable is set. Documentation on how
    to run the test and interpret the output is also included.

    This code has been tested on i386 and ppc64, and an earlier version of the
    code has received extensive testing on a number of architectures as part of
    the PREEMPT_RT patchset.

    Signed-off-by: "Paul E. McKenney"
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Paul E. McKenney