8ff12cfc00
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 15 So the skbuff_fclone_cache is of highest importance for the tbench load. Pretty high load on the 192 sized slab. Look for the aliases slabinfo -a | grep 000192 :0000192 <- xfs_btree_cur filp kmalloc-192 uid_cache tw_sock_TCP request_sock_TCPv6 tw_sock_TCPv6 skbuff_head_cache xfs_ili Likely skbuff_head_cache. Looking into the statistics of the skbuff_fclone_cache is possible through slabinfo skbuff_fclone_cache ->-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 111954404 Flushes 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 5299468 Deactivate 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 slab Fastpath: 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 processing Add 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 <clameter@sgi.com>
631 lines
22 KiB
Text
631 lines
22 KiB
Text
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config PRINTK_TIME
|
|
bool "Show timing information on printks"
|
|
depends on PRINTK
|
|
help
|
|
Selecting this option causes timing information to be
|
|
included in printk output. This allows you to measure
|
|
the interval between kernel operations, including bootup
|
|
operations. This is useful for identifying long delays
|
|
in kernel startup.
|
|
|
|
config ENABLE_WARN_DEPRECATED
|
|
bool "Enable __deprecated logic"
|
|
default y
|
|
help
|
|
Enable the __deprecated logic in the kernel build.
|
|
Disable this to suppress the "warning: 'foo' is deprecated
|
|
(declared at kernel/power/somefile.c:1234)" messages.
|
|
|
|
config ENABLE_MUST_CHECK
|
|
bool "Enable __must_check logic"
|
|
default y
|
|
help
|
|
Enable the __must_check logic in the kernel build. Disable this to
|
|
suppress the "warning: ignoring return value of 'foo', declared with
|
|
attribute warn_unused_result" messages.
|
|
|
|
config MAGIC_SYSRQ
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|
bool "Magic SysRq key"
|
|
depends on !UML
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help
|
|
If you say Y here, you will have some control over the system even
|
|
if the system crashes for example during kernel debugging (e.g., you
|
|
will be able to flush the buffer cache to disk, reboot the system
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immediately or dump some status information). This is accomplished
|
|
by pressing various keys while holding SysRq (Alt+PrintScreen). It
|
|
also works on a serial console (on PC hardware at least), if you
|
|
send a BREAK and then within 5 seconds a command keypress. The
|
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keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
|
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unless you really know what this hack does.
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|
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config UNUSED_SYMBOLS
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bool "Enable unused/obsolete exported symbols"
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default y if X86
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help
|
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Unused but exported symbols make the kernel needlessly bigger. For
|
|
that reason most of these unused exports will soon be removed. This
|
|
option is provided temporarily to provide a transition period in case
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some external kernel module needs one of these symbols anyway. If you
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encounter such a case in your module, consider if you are actually
|
|
using the right API. (rationale: since nobody in the kernel is using
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this in a module, there is a pretty good chance it's actually the
|
|
wrong interface to use). If you really need the symbol, please send a
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|
mail to the linux kernel mailing list mentioning the symbol and why
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|
you really need it, and what the merge plan to the mainline kernel for
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your module is.
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|
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config DEBUG_FS
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bool "Debug Filesystem"
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depends on SYSFS
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help
|
|
debugfs is a virtual file system that kernel developers use to put
|
|
debugging files into. Enable this option to be able to read and
|
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write to these files.
|
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|
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If unsure, say N.
|
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|
|
config HEADERS_CHECK
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|
bool "Run 'make headers_check' when building vmlinux"
|
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depends on !UML
|
|
help
|
|
This option will extract the user-visible kernel headers whenever
|
|
building the kernel, and will run basic sanity checks on them to
|
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ensure that exported files do not attempt to include files which
|
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were not exported, etc.
|
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|
|
If you're making modifications to header files which are
|
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relevant for userspace, say 'Y', and check the headers
|
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exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
|
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your build tree), to make sure they're suitable.
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|
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config DEBUG_SECTION_MISMATCH
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bool "Enable full Section mismatch analysis"
|
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depends on UNDEFINED
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help
|
|
The section mismatch analysis checks if there are illegal
|
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references from one section to another section.
|
|
Linux will during link or during runtime drop some sections
|
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and any use of code/data previously in these sections will
|
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most likely result in an oops.
|
|
In the code functions and variables are annotated with
|
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__init, __devinit etc. (see full list in include/linux/init.h)
|
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which results in the code/data being placed in specific sections.
|
|
The section mismatch analysis is always done after a full
|
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kernel build but enabling this option will in addition
|
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do the following:
|
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- Add the option -fno-inline-functions-called-once to gcc
|
|
When inlining a function annotated __init in a non-init
|
|
function we would lose the section information and thus
|
|
the analysis would not catch the illegal reference.
|
|
This option tells gcc to inline less but will also
|
|
result in a larger kernel.
|
|
- Run the section mismatch analysis for each module/built-in.o
|
|
When we run the section mismatch analysis on vmlinux.o we
|
|
lose valueble information about where the mismatch was
|
|
introduced.
|
|
Running the analysis for each module/built-in.o file
|
|
will tell where the mismatch happens much closer to the
|
|
source. The drawback is that we will report the same
|
|
mismatch at least twice.
|
|
- Enable verbose reporting from modpost to help solving
|
|
the section mismatches reported.
|
|
|
|
config DEBUG_KERNEL
|
|
bool "Kernel debugging"
|
|
help
|
|
Say Y here if you are developing drivers or trying to debug and
|
|
identify kernel problems.
|
|
|
|
config DEBUG_SHIRQ
|
|
bool "Debug shared IRQ handlers"
|
|
depends on DEBUG_KERNEL && GENERIC_HARDIRQS
|
|
help
|
|
Enable this to generate a spurious interrupt as soon as a shared
|
|
interrupt handler is registered, and just before one is deregistered.
|
|
Drivers ought to be able to handle interrupts coming in at those
|
|
points; some don't and need to be caught.
|
|
|
|
config DETECT_SOFTLOCKUP
|
|
bool "Detect Soft Lockups"
|
|
depends on DEBUG_KERNEL && !S390
|
|
default y
|
|
help
|
|
Say Y here to enable the kernel to detect "soft lockups",
|
|
which are bugs that cause the kernel to loop in kernel
|
|
mode for more than 10 seconds, without giving other tasks a
|
|
chance to run.
|
|
|
|
When a soft-lockup is detected, the kernel will print the
|
|
current stack trace (which you should report), but the
|
|
system will stay locked up. This feature has negligible
|
|
overhead.
|
|
|
|
(Note that "hard lockups" are separate type of bugs that
|
|
can be detected via the NMI-watchdog, on platforms that
|
|
support it.)
|
|
|
|
config SCHED_DEBUG
|
|
bool "Collect scheduler debugging info"
|
|
depends on DEBUG_KERNEL && PROC_FS
|
|
default y
|
|
help
|
|
If you say Y here, the /proc/sched_debug file will be provided
|
|
that can help debug the scheduler. The runtime overhead of this
|
|
option is minimal.
|
|
|
|
config SCHEDSTATS
|
|
bool "Collect scheduler statistics"
|
|
depends on DEBUG_KERNEL && PROC_FS
|
|
help
|
|
If you say Y here, additional code will be inserted into the
|
|
scheduler and related routines to collect statistics about
|
|
scheduler behavior and provide them in /proc/schedstat. These
|
|
stats may be useful for both tuning and debugging the scheduler
|
|
If you aren't debugging the scheduler or trying to tune a specific
|
|
application, you can say N to avoid the very slight overhead
|
|
this adds.
|
|
|
|
config TIMER_STATS
|
|
bool "Collect kernel timers statistics"
|
|
depends on DEBUG_KERNEL && PROC_FS
|
|
help
|
|
If you say Y here, additional code will be inserted into the
|
|
timer routines to collect statistics about kernel timers being
|
|
reprogrammed. The statistics can be read from /proc/timer_stats.
|
|
The statistics collection is started by writing 1 to /proc/timer_stats,
|
|
writing 0 stops it. This feature is useful to collect information
|
|
about timer usage patterns in kernel and userspace. This feature
|
|
is lightweight if enabled in the kernel config but not activated
|
|
(it defaults to deactivated on bootup and will only be activated
|
|
if some application like powertop activates it explicitly).
|
|
|
|
config DEBUG_SLAB
|
|
bool "Debug slab memory allocations"
|
|
depends on DEBUG_KERNEL && SLAB
|
|
help
|
|
Say Y here to have the kernel do limited verification on memory
|
|
allocation as well as poisoning memory on free to catch use of freed
|
|
memory. This can make kmalloc/kfree-intensive workloads much slower.
|
|
|
|
config DEBUG_SLAB_LEAK
|
|
bool "Memory leak debugging"
|
|
depends on DEBUG_SLAB
|
|
|
|
config SLUB_DEBUG_ON
|
|
bool "SLUB debugging on by default"
|
|
depends on SLUB && SLUB_DEBUG
|
|
default n
|
|
help
|
|
Boot with debugging on by default. SLUB boots by default with
|
|
the runtime debug capabilities switched off. Enabling this is
|
|
equivalent to specifying the "slub_debug" parameter on boot.
|
|
There is no support for more fine grained debug control like
|
|
possible with slub_debug=xxx. SLUB debugging may be switched
|
|
off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
|
|
"slub_debug=-".
|
|
|
|
config SLUB_STATS
|
|
default n
|
|
bool "Enable SLUB performance statistics"
|
|
depends on SLUB
|
|
help
|
|
SLUB statistics are useful to debug SLUBs allocation behavior in
|
|
order find ways to optimize the allocator. This should never be
|
|
enabled for production use since keeping statistics slows down
|
|
the allocator by a few percentage points. The slabinfo command
|
|
supports the determination of the most active slabs to figure
|
|
out which slabs are relevant to a particular load.
|
|
Try running: slabinfo -DA
|
|
|
|
config DEBUG_PREEMPT
|
|
bool "Debug preemptible kernel"
|
|
depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
|
|
default y
|
|
help
|
|
If you say Y here then the kernel will use a debug variant of the
|
|
commonly used smp_processor_id() function and will print warnings
|
|
if kernel code uses it in a preemption-unsafe way. Also, the kernel
|
|
will detect preemption count underflows.
|
|
|
|
config DEBUG_RT_MUTEXES
|
|
bool "RT Mutex debugging, deadlock detection"
|
|
depends on DEBUG_KERNEL && RT_MUTEXES
|
|
help
|
|
This allows rt mutex semantics violations and rt mutex related
|
|
deadlocks (lockups) to be detected and reported automatically.
|
|
|
|
config DEBUG_PI_LIST
|
|
bool
|
|
default y
|
|
depends on DEBUG_RT_MUTEXES
|
|
|
|
config RT_MUTEX_TESTER
|
|
bool "Built-in scriptable tester for rt-mutexes"
|
|
depends on DEBUG_KERNEL && RT_MUTEXES
|
|
help
|
|
This option enables a rt-mutex tester.
|
|
|
|
config DEBUG_SPINLOCK
|
|
bool "Spinlock and rw-lock debugging: basic checks"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Say Y here and build SMP to catch missing spinlock initialization
|
|
and certain other kinds of spinlock errors commonly made. This is
|
|
best used in conjunction with the NMI watchdog so that spinlock
|
|
deadlocks are also debuggable.
|
|
|
|
config DEBUG_MUTEXES
|
|
bool "Mutex debugging: basic checks"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
This feature allows mutex semantics violations to be detected and
|
|
reported.
|
|
|
|
config DEBUG_SEMAPHORE
|
|
bool "Semaphore debugging"
|
|
depends on DEBUG_KERNEL
|
|
depends on ALPHA || FRV
|
|
default n
|
|
help
|
|
If you say Y here then semaphore processing will issue lots of
|
|
verbose debugging messages. If you suspect a semaphore problem or a
|
|
kernel hacker asks for this option then say Y. Otherwise say N.
|
|
|
|
config DEBUG_LOCK_ALLOC
|
|
bool "Lock debugging: detect incorrect freeing of live locks"
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_MUTEXES
|
|
select LOCKDEP
|
|
help
|
|
This feature will check whether any held lock (spinlock, rwlock,
|
|
mutex or rwsem) is incorrectly freed by the kernel, via any of the
|
|
memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
|
|
vfree(), etc.), whether a live lock is incorrectly reinitialized via
|
|
spin_lock_init()/mutex_init()/etc., or whether there is any lock
|
|
held during task exit.
|
|
|
|
config PROVE_LOCKING
|
|
bool "Lock debugging: prove locking correctness"
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select LOCKDEP
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_MUTEXES
|
|
select DEBUG_LOCK_ALLOC
|
|
default n
|
|
help
|
|
This feature enables the kernel to prove that all locking
|
|
that occurs in the kernel runtime is mathematically
|
|
correct: that under no circumstance could an arbitrary (and
|
|
not yet triggered) combination of observed locking
|
|
sequences (on an arbitrary number of CPUs, running an
|
|
arbitrary number of tasks and interrupt contexts) cause a
|
|
deadlock.
|
|
|
|
In short, this feature enables the kernel to report locking
|
|
related deadlocks before they actually occur.
|
|
|
|
The proof does not depend on how hard and complex a
|
|
deadlock scenario would be to trigger: how many
|
|
participant CPUs, tasks and irq-contexts would be needed
|
|
for it to trigger. The proof also does not depend on
|
|
timing: if a race and a resulting deadlock is possible
|
|
theoretically (no matter how unlikely the race scenario
|
|
is), it will be proven so and will immediately be
|
|
reported by the kernel (once the event is observed that
|
|
makes the deadlock theoretically possible).
|
|
|
|
If a deadlock is impossible (i.e. the locking rules, as
|
|
observed by the kernel, are mathematically correct), the
|
|
kernel reports nothing.
|
|
|
|
NOTE: this feature can also be enabled for rwlocks, mutexes
|
|
and rwsems - in which case all dependencies between these
|
|
different locking variants are observed and mapped too, and
|
|
the proof of observed correctness is also maintained for an
|
|
arbitrary combination of these separate locking variants.
|
|
|
|
For more details, see Documentation/lockdep-design.txt.
|
|
|
|
config LOCKDEP
|
|
bool
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select STACKTRACE
|
|
select FRAME_POINTER if !X86 && !MIPS
|
|
select KALLSYMS
|
|
select KALLSYMS_ALL
|
|
|
|
config LOCK_STAT
|
|
bool "Lock usage statistics"
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select LOCKDEP
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_MUTEXES
|
|
select DEBUG_LOCK_ALLOC
|
|
default n
|
|
help
|
|
This feature enables tracking lock contention points
|
|
|
|
For more details, see Documentation/lockstat.txt
|
|
|
|
config DEBUG_LOCKDEP
|
|
bool "Lock dependency engine debugging"
|
|
depends on DEBUG_KERNEL && LOCKDEP
|
|
help
|
|
If you say Y here, the lock dependency engine will do
|
|
additional runtime checks to debug itself, at the price
|
|
of more runtime overhead.
|
|
|
|
config TRACE_IRQFLAGS
|
|
depends on DEBUG_KERNEL
|
|
bool
|
|
default y
|
|
depends on TRACE_IRQFLAGS_SUPPORT
|
|
depends on PROVE_LOCKING
|
|
|
|
config DEBUG_SPINLOCK_SLEEP
|
|
bool "Spinlock debugging: sleep-inside-spinlock checking"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
If you say Y here, various routines which may sleep will become very
|
|
noisy if they are called with a spinlock held.
|
|
|
|
config DEBUG_LOCKING_API_SELFTESTS
|
|
bool "Locking API boot-time self-tests"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Say Y here if you want the kernel to run a short self-test during
|
|
bootup. The self-test checks whether common types of locking bugs
|
|
are detected by debugging mechanisms or not. (if you disable
|
|
lock debugging then those bugs wont be detected of course.)
|
|
The following locking APIs are covered: spinlocks, rwlocks,
|
|
mutexes and rwsems.
|
|
|
|
config STACKTRACE
|
|
bool
|
|
depends on DEBUG_KERNEL
|
|
depends on STACKTRACE_SUPPORT
|
|
|
|
config DEBUG_KOBJECT
|
|
bool "kobject debugging"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
If you say Y here, some extra kobject debugging messages will be sent
|
|
to the syslog.
|
|
|
|
config DEBUG_HIGHMEM
|
|
bool "Highmem debugging"
|
|
depends on DEBUG_KERNEL && HIGHMEM
|
|
help
|
|
This options enables addition error checking for high memory systems.
|
|
Disable for production systems.
|
|
|
|
config DEBUG_BUGVERBOSE
|
|
bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
|
|
depends on BUG
|
|
depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BLACKFIN
|
|
default !EMBEDDED
|
|
help
|
|
Say Y here to make BUG() panics output the file name and line number
|
|
of the BUG call as well as the EIP and oops trace. This aids
|
|
debugging but costs about 70-100K of memory.
|
|
|
|
config DEBUG_INFO
|
|
bool "Compile the kernel with debug info"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
If you say Y here the resulting kernel image will include
|
|
debugging info resulting in a larger kernel image.
|
|
This adds debug symbols to the kernel and modules (gcc -g), and
|
|
is needed if you intend to use kernel crashdump or binary object
|
|
tools like crash, kgdb, LKCD, gdb, etc on the kernel.
|
|
Say Y here only if you plan to debug the kernel.
|
|
|
|
If unsure, say N.
|
|
|
|
config DEBUG_VM
|
|
bool "Debug VM"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to turn on extended checks in the virtual-memory system
|
|
that may impact performance.
|
|
|
|
If unsure, say N.
|
|
|
|
config DEBUG_LIST
|
|
bool "Debug linked list manipulation"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to turn on extended checks in the linked-list
|
|
walking routines.
|
|
|
|
If unsure, say N.
|
|
|
|
config DEBUG_SG
|
|
bool "Debug SG table operations"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to turn on checks on scatter-gather tables. This can
|
|
help find problems with drivers that do not properly initialize
|
|
their sg tables.
|
|
|
|
If unsure, say N.
|
|
|
|
config FRAME_POINTER
|
|
bool "Compile the kernel with frame pointers"
|
|
depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BLACKFIN)
|
|
default y if DEBUG_INFO && UML
|
|
help
|
|
If you say Y here the resulting kernel image will be slightly larger
|
|
and slower, but it might give very useful debugging information on
|
|
some architectures or if you use external debuggers.
|
|
If you don't debug the kernel, you can say N.
|
|
|
|
config FORCED_INLINING
|
|
bool "Force gcc to inline functions marked 'inline'"
|
|
depends on DEBUG_KERNEL
|
|
default y
|
|
help
|
|
This option determines if the kernel forces gcc to inline the functions
|
|
developers have marked 'inline'. Doing so takes away freedom from gcc to
|
|
do what it thinks is best, which is desirable for the gcc 3.x series of
|
|
compilers. The gcc 4.x series have a rewritten inlining algorithm and
|
|
disabling this option will generate a smaller kernel there. Hopefully
|
|
this algorithm is so good that allowing gcc4 to make the decision can
|
|
become the default in the future, until then this option is there to
|
|
test gcc for this.
|
|
|
|
config BOOT_PRINTK_DELAY
|
|
bool "Delay each boot printk message by N milliseconds"
|
|
depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
|
|
help
|
|
This build option allows you to read kernel boot messages
|
|
by inserting a short delay after each one. The delay is
|
|
specified in milliseconds on the kernel command line,
|
|
using "boot_delay=N".
|
|
|
|
It is likely that you would also need to use "lpj=M" to preset
|
|
the "loops per jiffie" value.
|
|
See a previous boot log for the "lpj" value to use for your
|
|
system, and then set "lpj=M" before setting "boot_delay=N".
|
|
NOTE: Using this option may adversely affect SMP systems.
|
|
I.e., processors other than the first one may not boot up.
|
|
BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
|
|
what it believes to be lockup conditions.
|
|
|
|
config RCU_TORTURE_TEST
|
|
tristate "torture tests for RCU"
|
|
depends on DEBUG_KERNEL
|
|
depends on m
|
|
default n
|
|
help
|
|
This option provides a kernel module that runs torture tests
|
|
on the RCU infrastructure. The kernel module may be built
|
|
after the fact on the running kernel to be tested, if desired.
|
|
|
|
Say M if you want the RCU torture tests to build as a module.
|
|
Say N if you are unsure.
|
|
|
|
config KPROBES_SANITY_TEST
|
|
bool "Kprobes sanity tests"
|
|
depends on DEBUG_KERNEL
|
|
depends on KPROBES
|
|
default n
|
|
help
|
|
This option provides for testing basic kprobes functionality on
|
|
boot. A sample kprobe, jprobe and kretprobe are inserted and
|
|
verified for functionality.
|
|
|
|
Say N if you are unsure.
|
|
|
|
config BACKTRACE_SELF_TEST
|
|
tristate "Self test for the backtrace code"
|
|
depends on DEBUG_KERNEL
|
|
default n
|
|
help
|
|
This option provides a kernel module that can be used to test
|
|
the kernel stack backtrace code. This option is not useful
|
|
for distributions or general kernels, but only for kernel
|
|
developers working on architecture code.
|
|
|
|
Say N if you are unsure.
|
|
|
|
config LKDTM
|
|
tristate "Linux Kernel Dump Test Tool Module"
|
|
depends on DEBUG_KERNEL
|
|
depends on KPROBES
|
|
default n
|
|
help
|
|
This module enables testing of the different dumping mechanisms by
|
|
inducing system failures at predefined crash points.
|
|
If you don't need it: say N
|
|
Choose M here to compile this code as a module. The module will be
|
|
called lkdtm.
|
|
|
|
Documentation on how to use the module can be found in
|
|
drivers/misc/lkdtm.c
|
|
|
|
config FAULT_INJECTION
|
|
bool "Fault-injection framework"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Provide fault-injection framework.
|
|
For more details, see Documentation/fault-injection/.
|
|
|
|
config FAILSLAB
|
|
bool "Fault-injection capability for kmalloc"
|
|
depends on FAULT_INJECTION
|
|
help
|
|
Provide fault-injection capability for kmalloc.
|
|
|
|
config FAIL_PAGE_ALLOC
|
|
bool "Fault-injection capabilitiy for alloc_pages()"
|
|
depends on FAULT_INJECTION
|
|
help
|
|
Provide fault-injection capability for alloc_pages().
|
|
|
|
config FAIL_MAKE_REQUEST
|
|
bool "Fault-injection capability for disk IO"
|
|
depends on FAULT_INJECTION
|
|
help
|
|
Provide fault-injection capability for disk IO.
|
|
|
|
config FAULT_INJECTION_DEBUG_FS
|
|
bool "Debugfs entries for fault-injection capabilities"
|
|
depends on FAULT_INJECTION && SYSFS && DEBUG_FS
|
|
help
|
|
Enable configuration of fault-injection capabilities via debugfs.
|
|
|
|
config FAULT_INJECTION_STACKTRACE_FILTER
|
|
bool "stacktrace filter for fault-injection capabilities"
|
|
depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
|
|
depends on !X86_64
|
|
select STACKTRACE
|
|
select FRAME_POINTER
|
|
help
|
|
Provide stacktrace filter for fault-injection capabilities
|
|
|
|
config LATENCYTOP
|
|
bool "Latency measuring infrastructure"
|
|
select FRAME_POINTER if !MIPS
|
|
select KALLSYMS
|
|
select KALLSYMS_ALL
|
|
select STACKTRACE
|
|
select SCHEDSTATS
|
|
select SCHED_DEBUG
|
|
depends on HAVE_LATENCYTOP_SUPPORT
|
|
help
|
|
Enable this option if you want to use the LatencyTOP tool
|
|
to find out which userspace is blocking on what kernel operations.
|
|
|
|
config PROVIDE_OHCI1394_DMA_INIT
|
|
bool "Provide code for enabling DMA over FireWire early on boot"
|
|
depends on PCI && X86
|
|
help
|
|
If you want to debug problems which hang or crash the kernel early
|
|
on boot and the crashing machine has a FireWire port, you can use
|
|
this feature to remotely access the memory of the crashed machine
|
|
over FireWire. This employs remote DMA as part of the OHCI1394
|
|
specification which is now the standard for FireWire controllers.
|
|
|
|
With remote DMA, you can monitor the printk buffer remotely using
|
|
firescope and access all memory below 4GB using fireproxy from gdb.
|
|
Even controlling a kernel debugger is possible using remote DMA.
|
|
|
|
Usage:
|
|
|
|
If ohci1394_dma=early is used as boot parameter, it will initialize
|
|
all OHCI1394 controllers which are found in the PCI config space.
|
|
|
|
As all changes to the FireWire bus such as enabling and disabling
|
|
devices cause a bus reset and thereby disable remote DMA for all
|
|
devices, be sure to have the cable plugged and FireWire enabled on
|
|
the debugging host before booting the debug target for debugging.
|
|
|
|
This code (~1k) is freed after boot. By then, the firewire stack
|
|
in charge of the OHCI-1394 controllers should be used instead.
|
|
|
|
See Documentation/debugging-via-ohci1394.txt for more information.
|
|
|
|
source "samples/Kconfig"
|