path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-21 19:26:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-21 19:26:51 -0700
commit226da0dbc84ed97f448523e2a4cb91c27fa68ed9 (patch)
tree3969a9f612cd5596747ecde2066e65eacbab7d2e /Documentation
parent5ec29e3149d800e6db83c1b6ff441daf319cbbe2 (diff)
parent2d84e023cb5ec00403ff5d447533c6fd58fcc7ff (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molnar: "This is the v3.5 RCU tree from Paul E. McKenney: 1) A set of improvements and fixes to the RCU_FAST_NO_HZ feature (with more on the way for 3.6). Posted to LKML: https://lkml.org/lkml/2012/4/23/324 (commits 1-3 and 5), https://lkml.org/lkml/2012/4/16/611 (commit 4), https://lkml.org/lkml/2012/4/30/390 (commit 6), and https://lkml.org/lkml/2012/5/4/410 (commit 7, combined with the other commits for the convenience of the tester). 2) Changes to make rcu_barrier() avoid disrupting execution of CPUs that have no RCU callbacks. Posted to LKML: https://lkml.org/lkml/2012/4/23/322. 3) A couple of commits that improve the efficiency of the interaction between preemptible RCU and the scheduler, these two being all that survived an abortive attempt to allow preemptible RCU's __rcu_read_lock() to be inlined. The full set was posted to LKML at https://lkml.org/lkml/2012/4/14/143, and the first and third patches of that set remain. 4) Lai Jiangshan's algorithmic implementation of SRCU, which includes call_srcu() and srcu_barrier(). A major feature of this new implementation is that synchronize_srcu() no longer disturbs the execution of other CPUs. This work is based on earlier implementations by Peter Zijlstra and Paul E. McKenney. Posted to LKML: https://lkml.org/lkml/2012/2/22/82. 5) A number of miscellaneous bug fixes and improvements which were posted to LKML at: https://lkml.org/lkml/2012/4/23/353 with subsequent updates posted to LKML." * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) rcu: Make rcu_barrier() less disruptive rcu: Explicitly initialize RCU_FAST_NO_HZ per-CPU variables rcu: Make RCU_FAST_NO_HZ handle timer migration rcu: Update RCU maintainership rcu: Make exit_rcu() more precise and consolidate rcu: Move PREEMPT_RCU preemption to switch_to() invocation rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU rcu: Add rcutorture test for call_srcu() rcu: Implement per-domain single-threaded call_srcu() state machine rcu: Use single value to handle expedited SRCU grace periods rcu: Improve srcu_readers_active_idx()'s cache locality rcu: Remove unused srcu_barrier() rcu: Implement a variant of Peter's SRCU algorithm rcu: Improve SRCU's wait_idx() comments rcu: Flip ->completed only once per SRCU grace period rcu: Increment upper bit only for srcu_read_lock() rcu: Remove fast check path from __synchronize_srcu() rcu: Direct algorithmic SRCU implementation rcu: Introduce rcutorture testing for rcu_barrier() timer: Fix mod_timer_pinned() header comment ...
Diffstat (limited to 'Documentation')
2 files changed, 99 insertions, 4 deletions
diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index 375d3fb7143..4ddf3913fd8 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -47,6 +47,16 @@ irqreader Says to invoke RCU readers from irq level. This is currently
permit this. (Or, more accurately, variants of RCU that do
-not- permit this know to ignore this variable.)
+n_barrier_cbs If this is nonzero, RCU barrier testing will be conducted,
+ in which case n_barrier_cbs specifies the number of
+ RCU callbacks (and corresponding kthreads) to use for
+ this testing. The value cannot be negative. If you
+ specify this to be non-zero when torture_type indicates a
+ synchronous RCU implementation (one for which a member of
+ the synchronize_rcu() rather than the call_rcu() family is
+ used -- see the documentation for torture_type below), an
+ error will be reported and no testing will be carried out.
nfakewriters This is the number of RCU fake writer threads to run. Fake
writer threads repeatedly use the synchronous "wait for
current readers" function of the interface selected by
@@ -188,7 +198,7 @@ OUTPUT
The statistics output is as follows:
rcu-torture:--- Start of test: nreaders=16 nfakewriters=4 stat_interval=30 verbose=0 test_no_idle_hz=1 shuffle_interval=3 stutter=5 irqreader=1 fqs_duration=0 fqs_holdoff=0 fqs_stutter=3 test_boost=1/0 test_boost_interval=7 test_boost_duration=4
- rcu-torture: rtc: (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 3055767
+ rcu-torture: rtc: (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0 rtbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 3055767
rcu-torture: Reader Pipe: 727860534 34213 0 0 0 0 0 0 0 0 0
rcu-torture: Reader Batch: 727877838 17003 0 0 0 0 0 0 0 0 0
rcu-torture: Free-Block Circulation: 155440 155440 155440 155440 155440 155440 155440 155440 155440 155440 0
@@ -230,6 +240,9 @@ o "rtmbe": A non-zero value indicates that rcutorture believes that
rcu_assign_pointer() and rcu_dereference() are not working
correctly. This value should be zero.
+o "rtbe": A non-zero value indicates that one of the rcu_barrier()
+ family of functions is not working correctly.
o "rtbke": rcutorture was unable to create the real-time kthreads
used to force RCU priority inversion. This value should be zero.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f995195409f..0e90453e4ac 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2333,18 +2333,100 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
See Documentation/blockdev/ramdisk.txt.
- rcupdate.blimit= [KNL,BOOT]
+ rcutree.blimit= [KNL,BOOT]
Set maximum number of finished RCU callbacks to process
in one batch.
- rcupdate.qhimark= [KNL,BOOT]
+ rcutree.qhimark= [KNL,BOOT]
Set threshold of queued
RCU callbacks over which batch limiting is disabled.
- rcupdate.qlowmark= [KNL,BOOT]
+ rcutree.qlowmark= [KNL,BOOT]
Set threshold of queued RCU callbacks below which
batch limiting is re-enabled.
+ rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
+ Suppress RCU CPU stall warning messages.
+ rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
+ Set timeout for RCU CPU stall warning messages.
+ rcutorture.fqs_duration= [KNL,BOOT]
+ Set duration of force_quiescent_state bursts.
+ rcutorture.fqs_holdoff= [KNL,BOOT]
+ Set holdoff time within force_quiescent_state bursts.
+ rcutorture.fqs_stutter= [KNL,BOOT]
+ Set wait time between force_quiescent_state bursts.
+ rcutorture.irqreader= [KNL,BOOT]
+ Test RCU readers from irq handlers.
+ rcutorture.n_barrier_cbs= [KNL,BOOT]
+ Set callbacks/threads for rcu_barrier() testing.
+ rcutorture.nfakewriters= [KNL,BOOT]
+ Set number of concurrent RCU writers. These just
+ stress RCU, they don't participate in the actual
+ test, hence the "fake".
+ rcutorture.nreaders= [KNL,BOOT]
+ Set number of RCU readers.
+ rcutorture.onoff_holdoff= [KNL,BOOT]
+ Set time (s) after boot for CPU-hotplug testing.
+ rcutorture.onoff_interval= [KNL,BOOT]
+ Set time (s) between CPU-hotplug operations, or
+ zero to disable CPU-hotplug testing.
+ rcutorture.shuffle_interval= [KNL,BOOT]
+ Set task-shuffle interval (s). Shuffling tasks
+ allows some CPUs to go into dyntick-idle mode
+ during the rcutorture test.
+ rcutorture.shutdown_secs= [KNL,BOOT]
+ Set time (s) after boot system shutdown. This
+ is useful for hands-off automated testing.
+ rcutorture.stall_cpu= [KNL,BOOT]
+ Duration of CPU stall (s) to test RCU CPU stall
+ warnings, zero to disable.
+ rcutorture.stall_cpu_holdoff= [KNL,BOOT]
+ Time to wait (s) after boot before inducing stall.
+ rcutorture.stat_interval= [KNL,BOOT]
+ Time (s) between statistics printk()s.
+ rcutorture.stutter= [KNL,BOOT]
+ Time (s) to stutter testing, for example, specifying
+ five seconds causes the test to run for five seconds,
+ wait for five seconds, and so on. This tests RCU's
+ ability to transition abruptly to and from idle.
+ rcutorture.test_boost= [KNL,BOOT]
+ Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
+ "Maybe" means test if the RCU implementation
+ under test support RCU priority boosting.
+ rcutorture.test_boost_duration= [KNL,BOOT]
+ Duration (s) of each individual boost test.
+ rcutorture.test_boost_interval= [KNL,BOOT]
+ Interval (s) between each boost test.
+ rcutorture.test_no_idle_hz= [KNL,BOOT]
+ Test RCU's dyntick-idle handling. See also the
+ rcutorture.shuffle_interval parameter.
+ rcutorture.torture_type= [KNL,BOOT]
+ Specify the RCU implementation to test.
+ rcutorture.verbose= [KNL,BOOT]
+ Enable additional printk() statements.
rdinit= [KNL]
Format: <full_path>
Run specified binary instead of /init from the ramdisk,