27 Jul, 2011
1 commit
-
This allows us to move duplicated code in
(atomic_inc_not_zero() for now) toSigned-off-by: Arun Sharma
Reviewed-by: Eric Dumazet
Cc: Ingo Molnar
Cc: David Miller
Cc: Eric Dumazet
Acked-by: Mike Frysinger
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Jul, 2011
1 commit
-
Since ca5ecddf (rcu: define __rcu address space modifier for sparse)
rcu_dereference_check use rcu_read_lock_held as a part of condition
automatically so callers do not have to do that as well.Signed-off-by: Michal Hocko
Acked-by: Paul E. McKenney
Signed-off-by: Jiri Kosina
06 May, 2011
4 commits
-
The CONFIG_DEBUG_OBJECTS_RCU_HEAD facility requires that on-stack RCU
callbacks be flagged explicitly to debug-objects using the
init_rcu_head_on_stack() and destroy_rcu_head_on_stack() functions.
This commit applies those functions to the rcutorture code that tests
RCU priority boosting.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
It is not possible to accurately correlate rcutorture output with that
of debugfs. This patch therefore adds a debugfs file that prints out
the rcutorture version number, permitting easy correlation.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
The n_rcu_torture_boost_allocerror and n_rcu_torture_boost_afferror
statistics are not actually incremented anymore, so eliminate them.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
The scheduler does not appear to take kindly to having multiple
real-time threads bound to a CPU that is going offline. So this
commit is a temporary hack-around to avoid that happening.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
05 Mar, 2011
1 commit
-
linux/sched.h is included twice in kernel/rcutorture.c - once is enough.
Signed-off-by: Jesper Juhl
Reviewed-by: Josh Triplett
Signed-off-by: Paul E. McKenney
08 Oct, 2010
1 commit
-
Add an optional test to force long-term preemption of RCU read-side
critical sections, controlled by new test_boost, test_boost_interval,
and test_boost_duration module parameters. This is to be used to
test RCU priority boosting.Signed-off-by: Paul E. McKenney
24 Sep, 2010
1 commit
-
Add the sparse __rcu address-space identifier and make a couple of
variables static.Signed-off-by: Paul E. McKenney
20 Aug, 2010
1 commit
-
Add random preemption to help we to torture the preemptable rcu.
srcu_read_delay() also calls rcu_read_delay() for shorter delays.
Added comment to preempt_schedule() call indicating that no quiescent
states happen if preemption is disabled.Signed-off-by: Lai Jiangshan
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett
09 Jun, 2010
1 commit
-
For people who otherwise get to write: cpu_clock(smp_processor_id()),
there is now: local_clock().Also, as per suggestion from Andrew, provide some documentation on
the various clock interfaces, and minimize the unsigned long long vs
u64 mess.Signed-off-by: Peter Zijlstra
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Jens Axboe
LKML-Reference:
Signed-off-by: Ingo Molnar
18 May, 2010
1 commit
-
…/git/tip/linux-2.6-tip
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits)
stop_machine: Move local variable closer to the usage site in cpu_stop_cpu_callback()
sched, wait: Use wrapper functions
sched: Remove a stale comment
ondemand: Make the iowait-is-busy time a sysfs tunable
ondemand: Solve a big performance issue by counting IOWAIT time as busy
sched: Intoduce get_cpu_iowait_time_us()
sched: Eliminate the ts->idle_lastupdate field
sched: Fold updating of the last_update_time_info into update_ts_time_stats()
sched: Update the idle statistics in get_cpu_idle_time_us()
sched: Introduce a function to update the idle statistics
sched: Add a comment to get_cpu_idle_time_us()
cpu_stop: add dummy implementation for UP
sched: Remove rq argument to the tracepoints
rcu: need barrier() in UP synchronize_sched_expedited()
sched: correctly place paranioa memory barriers in synchronize_sched_expedited()
sched: kill paranoia check in synchronize_sched_expedited()
sched: replace migration_thread with cpu_stop
stop_machine: reimplement using cpu_stop
cpu_stop: implement stop_cpu[s]()
sched: Fix select_idle_sibling() logic in select_task_rq_fair()
...
12 May, 2010
1 commit
-
Remove all rcu head inits. We don't care about the RCU head state before passing
it to call_rcu() anyway. Only leave the "on_stack" variants so debugobjects can
keep track of objects on stack.Signed-off-by: Mathieu Desnoyers
Signed-off-by: Paul E. McKenney
07 May, 2010
1 commit
-
Currently migration_thread is serving three purposes - migration
pusher, context to execute active_load_balance() and forced context
switcher for expedited RCU synchronize_sched. All three roles are
hardcoded into migration_thread() and determining which job is
scheduled is slightly messy.This patch kills migration_thread and replaces all three uses with
cpu_stop. The three different roles of migration_thread() are
splitted into three separate cpu_stop callbacks -
migration_cpu_stop(), active_load_balance_cpu_stop() and
synchronize_sched_expedited_cpu_stop() - and each use case now simply
asks cpu_stop to execute the callback as necessary.synchronize_sched_expedited() was implemented with private
preallocated resources and custom multi-cpu queueing and waiting
logic, both of which are provided by cpu_stop.
synchronize_sched_expedited_count is made atomic and all other shared
resources along with the mutex are dropped.synchronize_sched_expedited() also implemented a check to detect cases
where not all the callback got executed on their assigned cpus and
fall back to synchronize_sched(). If called with cpu hotplug blocked,
cpu_stop already guarantees that and the condition cannot happen;
otherwise, stop_machine() would break. However, this patch preserves
the paranoid check using a cpumask to record on which cpus the stopper
ran so that it can serve as a bisection point if something actually
goes wrong theree.Because the internal execution state is no longer visible,
rcu_expedited_torture_stats() is removed.This patch also renames cpu_stop threads to from "stopper/%d" to
"migration/%d". The names of these threads ultimately don't matter
and there's no reason to make unnecessary userland visible changes.With this patch applied, stop_machine() and sched now share the same
resources. stop_machine() is faster without wasting any resources and
sched migration users are much cleaner.Signed-off-by: Tejun Heo
Acked-by: Peter Zijlstra
Cc: Ingo Molnar
Cc: Dipankar Sarma
Cc: Josh Triplett
Cc: Paul E. McKenney
Cc: Oleg Nesterov
Cc: Dimitri Sivanich
03 Mar, 2010
1 commit
-
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: add __percpu sparse annotations to what's left
percpu: add __percpu sparse annotations to fs
percpu: add __percpu sparse annotations to core kernel subsystems
local_t: Remove leftover local.h
this_cpu: Remove pageset_notifier
this_cpu: Page allocator conversion
percpu, x86: Generic inc / dec percpu instructions
local_t: Move local.h include to ringbuffer.c and ring_buffer_benchmark.c
module: Use this_cpu_xx to dynamically allocate counters
local_t: Remove cpu_local_xx macros
percpu: refactor the code in pcpu_[de]populate_chunk()
percpu: remove compile warnings caused by __verify_pcpu_ptr()
percpu: make accessors check for percpu pointer in sparse
percpu: add __percpu for sparse.
percpu: make access macros universal
percpu: remove per_cpu__ prefix.
25 Feb, 2010
2 commits
-
The current "mod_timer(&t, 1)" potentially makes the timer fire
immediately, change this to wait one jiffy.Signed-off-by: Dan Carpenter
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Inspection is proving insufficient to catch all RCU misuses,
which is understandable given that rcu_dereference() might be
protected by any of four different flavors of RCU (RCU, RCU-bh,
RCU-sched, and SRCU), and might also/instead be protected by any
of a number of locking primitives. It is therefore time to
enlist the aid of lockdep.This set of patches is inspired by earlier work by Peter
Zijlstra and Thomas Gleixner, and takes the following approach:o Set up separate lockdep classes for RCU, RCU-bh, and RCU-sched.
o Set up separate lockdep classes for each instance of SRCU.
o Create primitives that check for being in an RCU read-side
critical section. These return exact answers if lockdep is
fully enabled, but if unsure, report being in an RCU read-side
critical section. (We want to avoid false positives!)
The primitives are:For RCU: rcu_read_lock_held(void)
For RCU-bh: rcu_read_lock_bh_held(void)
For RCU-sched: rcu_read_lock_sched_held(void)
For SRCU: srcu_read_lock_held(struct srcu_struct *sp)
o Add rcu_dereference_check(), which takes a second argument
in which one places a boolean expression based on the above
primitives and/or lockdep_is_held().o A new kernel configuration parameter, CONFIG_PROVE_RCU, enables
rcu_dereference_check(). This depends on CONFIG_PROVE_LOCKING,
and should be quite helpful during the transition period while
CONFIG_PROVE_RCU-unaware patches are in flight.The existing rcu_dereference() primitive does no checking, but
upcoming patches will change that.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
13 Jan, 2010
1 commit
-
Add force_quiescent_state() testing to rcutorture, with a
separate thread that repeatedly invokes force_quiescent_state()
in bursts. This can greatly increase the probability of
encountering certain types of race conditions.Suggested-by: Josh Triplett
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
05 Jan, 2010
1 commit
-
Conflicts:
arch/powerpc/platforms/pseries/hvCall.S
include/linux/percpu.h
15 Dec, 2009
1 commit
-
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (34 commits)
m68k: rename global variable vmalloc_end to m68k_vmalloc_end
percpu: add missing per_cpu_ptr_to_phys() definition for UP
percpu: Fix kdump failure if booted with percpu_alloc=page
percpu: make misc percpu symbols unique
percpu: make percpu symbols in ia64 unique
percpu: make percpu symbols in powerpc unique
percpu: make percpu symbols in x86 unique
percpu: make percpu symbols in xen unique
percpu: make percpu symbols in cpufreq unique
percpu: make percpu symbols in oprofile unique
percpu: make percpu symbols in tracer unique
percpu: make percpu symbols under kernel/ and mm/ unique
percpu: remove some sparse warnings
percpu: make alloc_percpu() handle array types
vmalloc: fix use of non-existent percpu variable in put_cpu_var()
this_cpu: Use this_cpu_xx in trace_functions_graph.c
this_cpu: Use this_cpu_xx for ftrace
this_cpu: Use this_cpu_xx in nmi handling
this_cpu: Use this_cpu operations in RCU
this_cpu: Use this_cpu ops for VM statistics
...Fix up trivial (famous last words) global per-cpu naming conflicts in
arch/x86/kvm/svm.c
mm/slab.c
03 Dec, 2009
1 commit
-
Implement an synchronize_rcu_expedited() for preemptible RCU
that actually is expedited. This uses
synchronize_sched_expedited() to force all threads currently
running in a preemptible-RCU read-side critical section onto the
appropriate ->blocked_tasks[] list, then takes a snapshot of all
of these lists and waits for them to drain.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
29 Oct, 2009
1 commit
-
Now that the return from alloc_percpu is compatible with the address
of per-cpu vars, it makes sense to hand around the address of per-cpu
variables. To make this sane, we remove the per_cpu__ prefix we used
created to stop people accidentally using these vars directly.Now we have sparse, we can use that (next patch).
tj: * Updated to convert stuff which were missed by or added after the
original patch.* Kill per_cpu_var() macro.
Signed-off-by: Rusty Russell
Signed-off-by: Tejun Heo
Reviewed-by: Christoph Lameter
26 Oct, 2009
2 commits
-
Make rcutorture list the available torture_type values when it
doesn't like the one specified.Signed-off-by: Paul E. McKenney
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar -
Adds the "srcu_expedited" torture type, and also renames
sched_ops_sync to sched_sync_ops for consistency while we are in
this file.Signed-off-by: Paul E. McKenney
Acked-by: Josh Triplett
Reviewed-by: Lai Jiangshan
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: avi@redhat.com
Cc: mtosatti@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
03 Oct, 2009
1 commit
-
RCU does not do dynamic allocations but it increments per cpu variables
a lot. These instructions results in a move to a register and then back
to memory. This patch will make it use the inc/dec instructions on x86
that do not need a register.Acked-by: Tejun Heo
Acked-by: Paul E. McKenney
Signed-off-by: Christoph Lameter
Signed-off-by: Tejun Heo
24 Sep, 2009
1 commit
-
Move declarations and update storage classes to make checkpatch happy.
Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference:
Signed-off-by: Ingo Molnar
19 Sep, 2009
1 commit
-
Fix a number of whitespace ^Ierrors in the include/linux/rcu*
and the kernel/rcu* files.Signed-off-by: Paul E. McKenney
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
LKML-Reference:
[ did more checkpatch fixlets ]
Signed-off-by: Ingo Molnar
18 Sep, 2009
1 commit
-
rcutorture already delays readers, but never for long enough to
make RCU force a quiescent state. Add an occasional delay of
50ms.Signed-off-by: Josh Triplett
Signed-off-by: Paul E. McKenney
Acked-by: Steven Rostedt
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
LKML-Reference:
Signed-off-by: Ingo Molnar
03 Jul, 2009
1 commit
-
This patch adds rcutorture tests for the new
synchronize_sched_expedited() primitive, and also does some
whitespace cleanups in kernel/rcutorture.c as well.Signed-off-by: Paul E. McKenney
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Cc: davem@davemloft.net
Cc: dada1@cosmosbay.com
Cc: zbr@ioremap.net
Cc: jeff.chua.linux@gmail.com
Cc: paulus@samba.org
Cc: laijs@cn.fujitsu.com
Cc: jengelh@medozas.de
Cc: r000n@r000n.net
Cc: benh@kernel.crashing.org
Cc: mathieu.desnoyers@polymtl.ca
LKML-Reference:
Signed-off-by: Ingo Molnar
30 Mar, 2009
1 commit
-
We're getting rid of cpumasks on the stack.
Simply change tmp_mask to a global, and allocate it in
rcu_torture_init().Signed-off-by: Rusty Russell
Acked-by: "Paul E. McKenney"
Cc: Josh Triplett
08 Jan, 2009
1 commit
-
This patch fixes an rcutorture bug found by Eric Sesterhenn that
resulted in oopses in response to "rmmod rcutorture". The problem
was in some new code that attempted to handle the case where a system
is shut down while rcutorture is still running, for example, when
rcutorture is built into the kernel so that it cannot be removed.
The fix causes the rcutorture threads to "park" in an
schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT) rather than
trying to get them to terminate cleanly. Concurrent shutdown and
rmmod is illegal.I believe that this is 2.6.29 material, as it is used in some testing
setups.For reference, here are the rcutorture operating modes:
CONFIG_RCU_TORTURE_TEST=m
This is the normal rcutorture build. Use "modprobe rcutorture"
(with optional arguments) to start, and "rmmod rcutorture" to
stop. If you shut the system down without doing the rmmod, you
should see console output like:rcutorture thread rcu_torture_writer parking due to system shutdown
One for each rcutorture kthread.
CONFIG_RCU_TORTURE_TEST=y
CONFIG_RCU_TORTURE_TEST_RUNNABLE=nUse this if you want rcutorture built in, but don't want the
test to start running during early boot. To start the
torturing:echo 1 > /proc/sys/kernel/rcutorture_runnable
To stop the torturing, s/1/0/
You will get "parking" console messages as noted above when
you shut the system down.CONFIG_RCU_TORTURE_TEST=y
CONFIG_RCU_TORTURE_TEST_RUNNABLE=ySame as above, except that the torturing starts during early
boot. Only for the stout of heart and strong of stomach.
The same /proc entry noted above may be used to control the
test.Located-by: Eric Sesterhenn
Tested-by: Eric Sesterhenn
Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar
05 Jan, 2009
1 commit
-
Fix an rcutorture bug that prevents the shutdown notifier from ever
actually having any effect, due to the fact that kthreads ignore all
signals.Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar
01 Jan, 2009
1 commit
-
Impact: use new cpumask API.
rcu_ctrlblk contains a cpumask, and it's highly optimized so I don't want
a cpumask_var_t (ie. a pointer) for the CONFIG_CPUMASK_OFFSTACK case. It
could use a dangling bitmap, and be allocated in __rcu_init to save memory,
but for the moment we use a bitmap.(Eventually 'struct cpumask' will be undefined for CONFIG_CPUMASK_OFFSTACK,
so we use a bitmap here to show we really mean it).We remove on-stack cpumasks, using cpumask_var_t for
rcu_torture_shuffle_tasks() and for_each_cpu_and in force_quiescent_state().Signed-off-by: Rusty Russell
17 Dec, 2008
1 commit
-
Impact: fix very rare reboot hang
Because rcutorture ignored all signals, it does not terminate in
response to the signals sent at shutdown time. This can cause strange
failures due to its continuing to make use of kernel function too late
in the shutdown sequence. This patch therefore adds a shutdown notifier
to rcutorture, causing it to shut down in response to a reboot or an
orderly shutdown.Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar
21 Oct, 2008
1 commit
-
A consolidated implementation will provide this generically through
asm/byteorder, remove direct includes to avoid breakage when the
changeover to the new implementation occurs.This hunk was lost from commit 1d8cca44b6a244b7e378546d719041819049a0f9
("byteorder: provide swabb.h generically in asm/byteorder.h")Signed-off-by: Harvey Harrison
Signed-off-by: Linus Torvalds
26 Jun, 2008
1 commit
-
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
24 Jun, 2008
2 commits
-
This patch aligns the rcutorture wakeup times to align with all other
multiple-of-a-second wakeups to further decrease power consumption.Suggested-by: Arjan van de Ven
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 -
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
19 Jun, 2008
1 commit
-
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
18 Jun, 2008
1 commit
-
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