30 Apr, 2008
2 commits
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Add calls to the generic object debugging infrastructure and provide fixup
functions which allow to keep the system alive when recoverable problems have
been detected by the object debugging core code.Signed-off-by: Thomas Gleixner
Acked-by: Ingo Molnar
Cc: Greg KH
Cc: Randy Dunlap
Cc: Kay Sievers
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
We can see an ever repeating problem pattern with objects of any kind in the
kernel:1) freeing of active objects
2) reinitialization of active objectsBoth problems can be hard to debug because the crash happens at a point where
we have no chance to decode the root cause anymore. One problem spot are
kernel timers, where the detection of the problem often happens in interrupt
context and usually causes the machine to panic.While working on a timer related bug report I had to hack specialized code
into the timer subsystem to get a reasonable hint for the root cause. This
debug hack was fine for temporary use, but far from a mergeable solution due
to the intrusiveness into the timer code.The code further lacked the ability to detect and report the root cause
instantly and keep the system operational.Keeping the system operational is important to get hold of the debug
information without special debugging aids like serial consoles and special
knowledge of the bug reporter.The problems described above are not restricted to timers, but timers tend to
expose it usually in a full system crash. Other objects are less explosive,
but the symptoms caused by such mistakes can be even harder to debug.Instead of creating specialized debugging code for the timer subsystem a
generic infrastructure is created which allows developers to verify their code
and provides an easy to enable debug facility for users in case of trouble.The debugobjects core code keeps track of operations on static and dynamic
objects by inserting them into a hashed list and sanity checking them on
object operations and provides additional checks whenever kernel memory is
freed.The tracked object operations are:
- initializing an object
- adding an object to a subsystem list
- deleting an object from a subsystem listEach operation is sanity checked before the operation is executed and the
subsystem specific code can provide a fixup function which allows to prevent
the damage of the operation. When the sanity check triggers a warning message
and a stack trace is printed.The list of operations can be extended if the need arises. For now it's
limited to the requirements of the first user (timers).The core code enqueues the objects into hash buckets. The hash index is
generated from the address of the object to simplify the lookup for the check
on kfree/vfree. Each bucket has it's own spinlock to avoid contention on a
global lock.The debug code can be compiled in without being active. The runtime overhead
is minimal and could be optimized by asm alternatives. A kernel command line
option enables the debugging code.Thanks to Ingo Molnar for review, suggestions and cleanup patches.
Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar
Cc: Greg KH
Cc: Randy Dunlap
Cc: Kay Sievers
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Apr, 2008
1 commit
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Add option to enable -Wframe-larger-than= on gcc 4.4
gcc mainline (upcoming 4.4) added a new -Wframe-larger-than=...
option to warn at build time about too large stack frames. Add a config
option to enable this warning, since this very useful for the kernel.I choose (somewhat arbitarily) 2048 as default warning threshold for 64bit
and 1024 as default for 32bit architectures. With some research and
fixing all the code for smaller values these defaults should be probably
lowered.With the default allyesconfigs have some new warnings, but I think
that is all code that should be just fixed.At some point (when gcc 4.4 is released and widely used) this should
obsolete make checkstackSigned-off-by: Andi Kleen
Signed-off-by: Sam Ravnborg
19 Apr, 2008
2 commits
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There have been a few oopses caused by 'struct file's with NULL f_vfsmnts.
There was also a set of potentially missed mnt_want_write()s from
dentry_open() calls.This patch provides a very simple debugging framework to catch these kinds of
bugs. It will WARN_ON() them, but should stop us from having any oopses or
mnt_writer count imbalances.I'm quite convinced that this is a good thing because it found bugs in the
stuff I was working on as soon as I wrote it.[hch: made it conditional on a debug option.
But it's still a little bit too ugly][hch: merged forced remount r/o fix from Dave and akpm's fix for the fix]
Signed-off-by: Dave Hansen
Acked-by: Al Viro
Signed-off-by: Christoph Hellwig
Signed-off-by: Andrew Morton
Signed-off-by: Al Viro -
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6: (43 commits)
firewire: cleanups
firewire: fix synchronization of gap counts
firewire: wait until PHY configuration packet was transmitted (fix bus reset loop)
firewire: remove unused struct member
firewire: use bitwise and to get reg in handle_registers
firewire: replace more hex values with defined csr constants
firewire: reread config ROM when device reset the bus
firewire: replace static ROM cache by allocated cache
firewire: fw-ohci: work around generation bug in TI controllers (fix AV/C and more)
firewire: fw-ohci: extend logging of bus generations and node ID
firewire: fw-ohci: conditionally log busReset interrupts
firewire: fw-ohci: don't append to AT context when it's not active
firewire: fw-ohci: log regAccessFail events
firewire: fw-ohci: make sure HCControl register LPS bit is set
firewire: fw-ohci: missing PPC PMac feature calls in failure path
firewire: fw-ohci: untangle a mixed unsigned/signed expression
firewire: debug interrupt events
firewire: fw-ohci: catch self_id_count == 0
firewire: fw-ohci: add self ID error check
firewire: fw-ohci: refactor probe, remove, suspend, resume
...
18 Apr, 2008
4 commits
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This way firewire-ohci can be used for remote debugging like ohci1394.
Version with amendment from Fri, 11 Apr 2008 00:08:08 +0200.Signed-off-by: Stefan Richter
Acked-by: Bernhard Kaindl -
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb:
kgdb: always use icache flush for sw breakpoints
kgdb: fix SMP NMI kgdb_handle_exception exit race
kgdb: documentation fixes
kgdb: allow static kgdbts boot configuration
kgdb: add documentation
kgdb: Kconfig fix
kgdb: add kgdb internal test suite
kgdb: fix several kgdb regressions
kgdb: kgdboc pl011 I/O module
kgdb: fix optional arch functions and probe_kernel_*
kgdb: add x86 HW breakpoints
kgdb: print breakpoint removed on exception
kgdb: clocksource watchdog
kgdb: fix NMI hangs
kgdb: fix kgdboc dynamic module configuration
kgdb: document parameters
x86: kgdb support
consoles: polling support, kgdboc
kgdb: core
uaccess: add probe_kernel_write() -
* 'semaphore' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc:
Remove DEBUG_SEMAPHORE from Kconfig
Improve semaphore documentation
Simplify semaphore implementation
Add down_timeout and change ACPI to use it
Introduce down_killable()
Generic semaphore implementation
Add semaphore.h to kernel_lock.c
Fix quota.h includes -
kgdb core code. Handles the protocol and the arch details.
[ mingo@elte.hu: heavily modified, simplified and cleaned up. ]
[ xemul@openvz.org: use find_task_by_pid_ns ]Signed-off-by: Jason Wessel
Signed-off-by: Ingo Molnar
Signed-off-by: Jan Kiszka
Reviewed-by: Thomas Gleixner
17 Apr, 2008
1 commit
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Alpha and FRV mutexes had an option to print lots of debugging messages
in their semaphore implementation. This feature has not been carried
over to the generic semaphores, so remove the stale Kconfig option.Signed-off-by: Matthew Wilcox
14 Apr, 2008
1 commit
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count_partial() is used by both slabinfo and the sysfs proc support. Move
the function directly before the beginning of the sysfs code so that it can
be easily found. Rework the preprocessor conditional to take into account
that slub sysfs support depends on CONFIG_SYSFS *and* CONFIG_SLUB_DEBUG.Make CONFIG_SLUB_STATS depend on CONFIG_SLUB_DEBUG and CONFIG_SYSFS. There
is no point of keeping statistics if no one can restrive them.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
24 Feb, 2008
1 commit
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Make LKDTM depend on BLOCK to prevent build failures with certain configs.
Signed-off-by: Chris Snook
Acked-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Feb, 2008
1 commit
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We started to see patches enabling this - so explain why
it is disabled and the condition to enable it again.Signed-off-by: Sam Ravnborg
10 Feb, 2008
1 commit
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Other than the defconfigs, remove the entry in compiler-gcc4.h,
Kconfig.debug and feature-removal-schedule.txt.Signed-off-by: Harvey Harrison
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
09 Feb, 2008
1 commit
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Add architecture support for the MN10300/AM33 CPUs produced by MEI to the
kernel.This patch also adds board support for the ASB2303 with the ASB2308 daughter
board, and the ASB2305. The only processor supported is the MN103E010, which
is an AM33v2 core plus on-chip devices.[akpm@linux-foundation.org: nuke cvs control strings]
Signed-off-by: Masakazu Urade
Signed-off-by: Koichi Yasutake
Signed-off-by: David Howells
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Feb, 2008
1 commit
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The statistics provided here allow the monitoring of allocator behavior but
at the cost of some (minimal) loss of performance. Counters are placed in
SLUB's per cpu data structure. The per cpu structure may be extended by the
statistics to grow larger than one cacheline which will increase the cache
footprint of SLUB.There is a compile option to enable/disable the inclusion of the runtime
statistics and its off by default.The slabinfo tool is enhanced to support these statistics via two options:
-D Switches the line of information displayed for a slab from size
mode to activity mode.-A Sorts the slabs displayed by activity. This allows the display of
the slabs most important to the performance of a certain load.-r Report option will report detailed statistics on
Example (tbench load):
slabinfo -AD ->Shows the most active slabs
Name Objects Alloc Free %Fast
skbuff_fclone_cache 33 111953835 111953835 99 99
:0000192 2666 5283688 5281047 99 99
:0001024 849 5247230 5246389 83 83
vm_area_struct 1349 119642 118355 91 22
:0004096 15 66753 66751 98 98
:0000064 2067 25297 23383 98 78
dentry 10259 28635 18464 91 45
:0000080 11004 18950 8089 98 98
:0000096 1703 12358 10784 99 98
:0000128 762 10582 9875 94 18
:0000512 184 9807 9647 95 81
:0002048 479 9669 9195 83 65
anon_vma 777 9461 9002 99 71
kmalloc-8 6492 9981 5624 99 97
:0000768 258 7174 6931 58 15So the skbuff_fclone_cache is of highest importance for the tbench load.
Pretty high load on the 192 sized slab. Look for the aliasesslabinfo -a | grep 000192
:0000192 -r option implied if cache name is mentioned.... Usual output ...
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 111953360 111946981 99 99
Slowpath 1044 7423 0 0
Page Alloc 272 264 0 0
Add partial 25 325 0 0
Remove partial 86 264 0 0
RemoteObj/SlabFrozen 350 4832 0 0
Total 111954404 111954404Flushes 49 Refill 0
Deactivate Full=325(92%) Empty=0(0%) ToHead=24(6%) ToTail=1(0%)Looks good because the fastpath is overwhelmingly taken.
skbuff_head_cache:
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 5297262 5259882 99 99
Slowpath 4477 39586 0 0
Page Alloc 937 824 0 0
Add partial 0 2515 0 0
Remove partial 1691 824 0 0
RemoteObj/SlabFrozen 2621 9684 0 0
Total 5301739 5299468Deactivate Full=2620(100%) Empty=0(0%) ToHead=0(0%) ToTail=0(0%)
Descriptions of the output:
Total: The total number of allocation and frees that occurred for a
slabFastpath: The number of allocations/frees that used the fastpath.
Slowpath: Other allocations
Page Alloc: Number of calls to the page allocator as a result of slowpath
processingAdd Partial: Number of slabs added to the partial list through free or
alloc (occurs during cpuslab flushes)Remove Partial: Number of slabs removed from the partial list as a result of
allocations retrieving a partial slab or by a free freeing
the last object of a slab.RemoteObj/Froz: How many times were remotely freed object encountered when a
slab was about to be deactivated. Frozen: How many times was
free able to skip list processing because the slab was in use
as the cpuslab of another processor.Flushes: Number of times the cpuslab was flushed on request
(kmem_cache_shrink, may result from races in __slab_alloc)Refill: Number of times we were able to refill the cpuslab from
remotely freed objects for the same slab.Deactivate: Statistics how slabs were deactivated. Shows how they were
put onto the partial list.In general fastpath is very good. Slowpath without partial list processing is
also desirable. Any touching of partial list uses node specific locks which
may potentially cause list lock contention.Signed-off-by: Christoph Lameter
03 Feb, 2008
2 commits
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Including additional fixes from Randy Dunlap
Signed-off-by: Geert Uytterhoeven
Signed-off-by: Sam Ravnborg -
We have too many section mismatches detected at the moment.
So silence modpost and prevent the option from being
set in a typical allyesconfig build.Tell the user how to see all the deteils in the summary
message from modpost.Signed-off-by: Sam Ravnborg
02 Feb, 2008
1 commit
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Change latencytop Kconfig entry so it doesn't list the archictectures
that support it. Instead introduce HAVE_LATENCY_SUPPORT which any
architecture can set. Should reduce patch conflicts.Cc: Arjan van de Ven
Cc: Martin Schwidefsky
Cc: Holger Wolf
Signed-off-by: Heiko Carstens
Signed-off-by: Ingo Molnar
30 Jan, 2008
3 commits
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This patch adds a new configuration option, which adds support for a new
early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch()
to decide wether OHCI-1394 FireWire controllers should be initialized and
enabled for physical DMA access to allow remote debugging of early problems
like issues ACPI or other subsystems which are executed very early.If the config option is not enabled, no code is changed, and if the boot
paramenter is not given, no new code is executed, and independent of that,
all new code is freed after boot, so the config option can be even enabled
in standard, non-debug kernels.With specialized tools, it is then possible to get debugging information
from machines which have no serial ports (notebooks) such as the printk
buffer contents, or any data which can be referenced from global pointers,
if it is stored below the 4GB limit and even memory dumps of of the physical
RAM region below the 4GB limit can be taken without any cooperation from the
CPU of the host, so the machine can be crashed early, it does not matter.In the extreme, even kernel debuggers can be accessed in this way. I wrote
a small kgdb module and an accompanying gdb stub for FireWire which allows
to gdb to talk to kgdb using remote remory reads and writes over FireWire.An version of the gdb stub fore FireWire is able to read all global data
from a system which is running a a normal kernel without any kernel debugger,
without any interruption or support of the system's CPU. That way, e.g. the
task struct and so on can be read and even manipulated when the physical DMA
access is granted.A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt
and I've put a copy online at
ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txtIt also has links to all the tools which are available to make use of it
another copy of it is online at:
ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diffSigned-Off-By: Bernhard Kaindl
Tested-By: Thomas Renninger
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
During the work on the x86 32 and 64 bit backtrace code I found it useful
to have a simple test module to test a process and irq context backtrace.
Since the existing backtrace code was buggy, I figure it might be useful
to have such a test module in the kernel so that maybe we can even
detect such bugs earlier..[ mingo@elte.hu: build fix ]
Signed-off-by: Arjan van de Ven
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
Here is a quick and naive smoke test for kprobes. This is intended to
just verify if some unrelated change broke the *probes subsystem. It is
self contained, architecture agnostic and isn't of any great use by itself.This needs to be built in the kernel and runs a basic set of tests to
verify if kprobes, jprobes and kretprobes run fine on the kernel. In case
of an error, it'll print out a message with a "BUG" prefix.This is a start; we intend to add more tests to this bucket over time.
Thanks to Jim Keniston and Masami Hiramatsu for comments and suggestions.
Tested on x86 (32/64) and powerpc.
Signed-off-by: Ananth N Mavinakayanahalli
Acked-by: Masami Hiramatsu
Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar
29 Jan, 2008
2 commits
-
If the config option CONFIG_SECTION_MISMATCH is not set and
we see a Section mismatch present the following to the user:modpost: Found 1 section mismatch(es).
To see additional details select "Enable full Section mismatch analysis"
in the Kernel Hacking menu (CONFIG_SECTION_MISMATCH).If the option CONFIG_SECTION_MISMATCH is selected
then be verbose in the Section mismatch reporting from mdopost.
Sample outputs:WARNING: o-x86_64/vmlinux.o(.text+0x7396): Section mismatch in reference from the function discover_ebda() to the variable .init.data:ebda_addr
The function discover_ebda() references
the variable __initdata ebda_addr.
This is often because discover_ebda lacks a __initdata
annotation or the annotation of ebda_addr is wrong.WARNING: o-x86_64/vmlinux.o(.data+0x74d58): Section mismatch in reference from the variable pci_serial_quirks to the function .devexit.text:pci_plx9050_exit()
The variable pci_serial_quirks references
the function __devexit pci_plx9050_exit()
If the reference is valid then annotate the
variable with __exit* (see linux/init.h) or name the variable:
*driver, *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,WARNING: o-x86_64/vmlinux.o(__ksymtab+0x630): Section mismatch in reference from the variable __ksymtab_arch_register_cpu to the function .cpuinit.text:arch_register_cpu()
The symbol arch_register_cpu is exported and annotated __cpuinit
Fix this by removing the __cpuinit annotation of arch_register_cpu or drop the export.Signed-off-by: Sam Ravnborg
-
Setting the option DEBUG_SECTION_MISMATCH will
report additional section mismatch'es but this
should in the end makes it possible to get rid of
all of them.See help text in lib/Kconfig.debug for details.
Signed-off-by: Sam Ravnborg
26 Jan, 2008
1 commit
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LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.Signed-off-by: Arjan van de Ven
Signed-off-by: Ingo Molnar
23 Nov, 2007
1 commit
-
Signed-off-by: Mike Frysinger
Signed-off-by: Bryan Wu
26 Oct, 2007
1 commit
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The __deprecated marker is quite useful in highlighting the remnants of
old APIs that want removing.However, it is quite normal for one or more years to pass, before the
(usually ancient, bitrotten) code in question is either updated or
deleted.Thus, like __must_check, add a Kconfig option that permits the silencing
of this compiler warning.This change mimics the ifdef-ery and Kconfig defaults of MUST_CHECK as
closely as possible.Signed-off-by: Jeff Garzik
Signed-off-by: Linus Torvalds
23 Oct, 2007
1 commit
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Add a Kconfig entry which will toggle some sanity checks on the sg
entry and tables.Signed-off-by: Jens Axboe
20 Oct, 2007
1 commit
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Begin infrastructure for kernel code samples in the samples/ directory.
Add its Kconfig and Kbuild files.
Source its Kconfig file in all arch/ Kconfigs.Signed-off-by: Randy Dunlap
Signed-off-by: Mathieu Desnoyers
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Oct, 2007
1 commit
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Optionally add a boot delay after each kernel printk() call, crudely
measured in milliseconds, with a maximum delay of 10 seconds per printk.Enable CONFIG_BOOT_PRINTK_DELAY=y and then add (e.g.):
"lpj=loops_per_jiffy boot_delay=100"
to the kernel command line.It has been useful in cases like "during boot, my machine just reboots or the
screen goes black" by slowing down printk, (and adding initcall_debug), we can
usually see the last thing that happened before the lights went out which is
usually a valuable clue.[akpm@linux-foundation.org: not all architectures implement CONFIG_HZ]
[akpm@linux-foundation.org: fix lots of stuff]
[bunk@stusta.de: kernel/printk.c: make 2 variables static]
[heiko.carstens@de.ibm.com: fix slow down printk on boot compile error]
Signed-off-by: Randy Dunlap
Signed-off-by: Dave Jones
Signed-off-by: Adrian Bunk
Signed-off-by: Heiko Carstens
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Oct, 2007
1 commit
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* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc: (408 commits)
[POWERPC] Add memchr() to the bootwrapper
[POWERPC] Implement logging of unhandled signals
[POWERPC] Add legacy serial support for OPB with flattened device tree
[POWERPC] Use 1TB segments
[POWERPC] XilinxFB: Allow fixed framebuffer base address
[POWERPC] XilinxFB: Add support for custom screen resolution
[POWERPC] XilinxFB: Use pdata to pass around framebuffer parameters
[POWERPC] PCI: Add 64-bit physical address support to setup_indirect_pci
[POWERPC] 4xx: Kilauea defconfig file
[POWERPC] 4xx: Kilauea DTS
[POWERPC] 4xx: Add AMCC Kilauea eval board support to platforms/40x
[POWERPC] 4xx: Add AMCC 405EX support to cputable.c
[POWERPC] Adjust TASK_SIZE on ppc32 systems to 3GB that are capable
[POWERPC] Use PAGE_OFFSET to tell if an address is user/kernel in SW TLB handlers
[POWERPC] 85xx: Enable FP emulation in MPC8560 ADS defconfig
[POWERPC] 85xx: Killed
[POWERPC] 85xx: Add cpm nodes for 8541/8555 CDS
[POWERPC] 85xx: Convert mpc8560ads to the new CPM binding.
[POWERPC] mpc8272ads: Remove muram from the CPM reg property.
[POWERPC] Make clockevents work on PPC601 processors
...Fixed up conflict in Documentation/powerpc/booting-without-of.txt manually.
08 Oct, 2007
1 commit
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Provide some documentation for CONFIG_LOCK_STAT.
Signed-off-by: Peter Zijlstra
Acked-by: Ingo Molnar
Cc: "Randy.Dunlap"
Cc: Rob Landley
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
03 Oct, 2007
2 commits
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Add CONFIG_DEBUG_PREEMPT support to ppc64: it was useful for testing
get_paca() preemption. Cheat a little, just use debug_smp_processor_id()
in the debug version of get_paca(): it contains all the right checks and
reporting, though get_paca() doesn't really use smp_processor_id().Use local_paca for what might have been called __raw_get_paca().
Silence harmless warnings from io.h and lparcfg.c with local_paca -
it is okay for iseries_lparcfg_data to be referencing shared_proc
with preemption enabled: all cpus should show the same value for
shared_proc.Why do other architectures need TRACE_IRQFLAGS_SUPPORT for DEBUG_PREEMPT?
I don't know, ppc64 appears to get along fine without it.Signed-off-by: Hugh Dickins
Signed-off-by: Paul Mackerras
25 Sep, 2007
1 commit
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Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Aug, 2007
1 commit
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The arm26 port has been in a state where it was far from even compiling
for quite some time.Ian Molton agreed with the removal.
Signed-off-by: Adrian Bunk
Cc: Ian Molton
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Jul, 2007
1 commit
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Introduce the core lock statistics code.
Lock statistics provides lock wait-time and hold-time (as well as the count
of corresponding contention and acquisitions events). Also, the first few
call-sites that encounter contention are tracked.Lock wait-time is the time spent waiting on the lock. This provides insight
into the locking scheme, that is, a heavily contended lock is indicative of
a too coarse locking scheme.Lock hold-time is the duration the lock was held, this provides a reference for
the wait-time numbers, so they can be put into perspective.1)
lock
2)
... do stuff ..
unlock
3)The time between 1 and 2 is the wait-time. The time between 2 and 3 is the
hold-time.The lockdep held-lock tracking code is reused, because it already collects locks
into meaningful groups (classes), and because it is an existing infrastructure
for lock instrumentation.Currently lockdep tracks lock acquisition with two hooks:
lock()
lock_acquire()
_lock()... code protected by lock ...
unlock()
lock_release()
_unlock()We need to extend this with two more hooks, in order to measure contention.
lock_contended() - used to measure contention events
lock_acquired() - completion of the contentionThese are then placed the following way:
lock()
lock_acquire()
if (!_try_lock())
lock_contended()
_lock()
lock_acquired()... do locked stuff ...
unlock()
lock_release()
_unlock()(Note: the try_lock() 'trick' is used to avoid instrumenting all platform
dependent lock primitive implementations.)It is also possible to toggle the two lockdep features at runtime using:
/proc/sys/kernel/prove_locking
/proc/sys/kernel/lock_stat(esp. turning off the O(n^2) prove_locking functionaliy can help)
[akpm@linux-foundation.org: build fixes]
[akpm@linux-foundation.org: nuke unneeded ifdefs]
Signed-off-by: Peter Zijlstra
Acked-by: Ingo Molnar
Acked-by: Jason Baron
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Jul, 2007
1 commit
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Add a new configuration variable
CONFIG_SLUB_DEBUG_ON
If set then the kernel will be booted by default with slab debugging
switched on. Similar to CONFIG_SLAB_DEBUG. By default slab debugging
is available but must be enabled by specifying "slub_debug" as a
kernel parameter.Also add support to switch off slab debugging for a kernel that was
built with CONFIG_SLUB_DEBUG_ON. This works by specifyingslub_debug=-
as a kernel parameter.
Dave Jones wanted this feature.
http://marc.info/?l=linux-kernel&m=118072189913045&w=2[akpm@linux-foundation.org: clean up switch statement]
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
10 Jul, 2007
1 commit
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enable CONFIG_SCHED_DEBUG in lib/Kconfig.debug.
the runtime overhead of this option is very small.
Signed-off-by: Ingo Molnar
01 Jun, 2007
1 commit
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Make timer-stats have almost zero overhead when enabled in the config but
not used. (this way distros can enable it more easily)Also update the documentation about overhead of timer_stats - it was
written for the first version which had a global lock and a linear list
walk based lookup ;-)Signed-off-by: Ingo Molnar
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds