Merge branch 'rcu/next' of git://github.com/paulmckrcu/linux into core/rcu
This commit is contained in:
Ingo Molnar
@@ -95,7 +95,7 @@ not to return until all ongoing NMI handlers exit. It is therefore safe
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to free up the handler's data as soon as synchronize_sched() returns.
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Important note: for this to work, the architecture in question must
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invoke irq_enter() and irq_exit() on NMI entry and exit, respectively.
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invoke nmi_enter() and nmi_exit() on NMI entry and exit, respectively.
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Answer to Quick Quiz
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110
Documentation/RCU/lockdep-splat.txt
Normal file
110
Documentation/RCU/lockdep-splat.txt
Normal file
@@ -0,0 +1,110 @@
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Lockdep-RCU was added to the Linux kernel in early 2010
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(http://lwn.net/Articles/371986/). This facility checks for some common
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misuses of the RCU API, most notably using one of the rcu_dereference()
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family to access an RCU-protected pointer without the proper protection.
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When such misuse is detected, an lockdep-RCU splat is emitted.
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The usual cause of a lockdep-RCU slat is someone accessing an
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RCU-protected data structure without either (1) being in the right kind of
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RCU read-side critical section or (2) holding the right update-side lock.
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This problem can therefore be serious: it might result in random memory
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overwriting or worse. There can of course be false positives, this
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being the real world and all that.
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So let's look at an example RCU lockdep splat from 3.0-rc5, one that
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has long since been fixed:
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===============================
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[ INFO: suspicious RCU usage. ]
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-------------------------------
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block/cfq-iosched.c:2776 suspicious rcu_dereference_protected() usage!
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other info that might help us debug this:
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rcu_scheduler_active = 1, debug_locks = 0
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3 locks held by scsi_scan_6/1552:
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#0: (&shost->scan_mutex){+.+.+.}, at: [<ffffffff8145efca>]
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scsi_scan_host_selected+0x5a/0x150
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#1: (&eq->sysfs_lock){+.+...}, at: [<ffffffff812a5032>]
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elevator_exit+0x22/0x60
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#2: (&(&q->__queue_lock)->rlock){-.-...}, at: [<ffffffff812b6233>]
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cfq_exit_queue+0x43/0x190
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stack backtrace:
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Pid: 1552, comm: scsi_scan_6 Not tainted 3.0.0-rc5 #17
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Call Trace:
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[<ffffffff810abb9b>] lockdep_rcu_dereference+0xbb/0xc0
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[<ffffffff812b6139>] __cfq_exit_single_io_context+0xe9/0x120
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[<ffffffff812b626c>] cfq_exit_queue+0x7c/0x190
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[<ffffffff812a5046>] elevator_exit+0x36/0x60
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[<ffffffff812a802a>] blk_cleanup_queue+0x4a/0x60
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[<ffffffff8145cc09>] scsi_free_queue+0x9/0x10
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[<ffffffff81460944>] __scsi_remove_device+0x84/0xd0
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[<ffffffff8145dca3>] scsi_probe_and_add_lun+0x353/0xb10
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[<ffffffff817da069>] ? error_exit+0x29/0xb0
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[<ffffffff817d98ed>] ? _raw_spin_unlock_irqrestore+0x3d/0x80
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[<ffffffff8145e722>] __scsi_scan_target+0x112/0x680
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[<ffffffff812c690d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
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[<ffffffff817da069>] ? error_exit+0x29/0xb0
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[<ffffffff812bcc60>] ? kobject_del+0x40/0x40
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[<ffffffff8145ed16>] scsi_scan_channel+0x86/0xb0
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[<ffffffff8145f0b0>] scsi_scan_host_selected+0x140/0x150
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[<ffffffff8145f149>] do_scsi_scan_host+0x89/0x90
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[<ffffffff8145f170>] do_scan_async+0x20/0x160
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[<ffffffff8145f150>] ? do_scsi_scan_host+0x90/0x90
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[<ffffffff810975b6>] kthread+0xa6/0xb0
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[<ffffffff817db154>] kernel_thread_helper+0x4/0x10
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[<ffffffff81066430>] ? finish_task_switch+0x80/0x110
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[<ffffffff817d9c04>] ? retint_restore_args+0xe/0xe
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[<ffffffff81097510>] ? __init_kthread_worker+0x70/0x70
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[<ffffffff817db150>] ? gs_change+0xb/0xb
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Line 2776 of block/cfq-iosched.c in v3.0-rc5 is as follows:
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if (rcu_dereference(ioc->ioc_data) == cic) {
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This form says that it must be in a plain vanilla RCU read-side critical
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section, but the "other info" list above shows that this is not the
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case. Instead, we hold three locks, one of which might be RCU related.
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And maybe that lock really does protect this reference. If so, the fix
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is to inform RCU, perhaps by changing __cfq_exit_single_io_context() to
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take the struct request_queue "q" from cfq_exit_queue() as an argument,
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which would permit us to invoke rcu_dereference_protected as follows:
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if (rcu_dereference_protected(ioc->ioc_data,
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lockdep_is_held(&q->queue_lock)) == cic) {
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With this change, there would be no lockdep-RCU splat emitted if this
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code was invoked either from within an RCU read-side critical section
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or with the ->queue_lock held. In particular, this would have suppressed
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the above lockdep-RCU splat because ->queue_lock is held (see #2 in the
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list above).
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On the other hand, perhaps we really do need an RCU read-side critical
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section. In this case, the critical section must span the use of the
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return value from rcu_dereference(), or at least until there is some
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reference count incremented or some such. One way to handle this is to
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add rcu_read_lock() and rcu_read_unlock() as follows:
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rcu_read_lock();
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if (rcu_dereference(ioc->ioc_data) == cic) {
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spin_lock(&ioc->lock);
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rcu_assign_pointer(ioc->ioc_data, NULL);
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spin_unlock(&ioc->lock);
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}
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rcu_read_unlock();
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With this change, the rcu_dereference() is always within an RCU
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read-side critical section, which again would have suppressed the
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above lockdep-RCU splat.
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But in this particular case, we don't actually deference the pointer
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returned from rcu_dereference(). Instead, that pointer is just compared
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to the cic pointer, which means that the rcu_dereference() can be replaced
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by rcu_access_pointer() as follows:
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if (rcu_access_pointer(ioc->ioc_data) == cic) {
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Because it is legal to invoke rcu_access_pointer() without protection,
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this change would also suppress the above lockdep-RCU splat.
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@@ -32,9 +32,27 @@ checking of rcu_dereference() primitives:
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srcu_dereference(p, sp):
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Check for SRCU read-side critical section.
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rcu_dereference_check(p, c):
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Use explicit check expression "c". This is useful in
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code that is invoked by both readers and updaters.
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rcu_dereference_raw(p)
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Use explicit check expression "c" along with
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||||
rcu_read_lock_held(). This is useful in code that is
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||||
invoked by both RCU readers and updaters.
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||||
rcu_dereference_bh_check(p, c):
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||||
Use explicit check expression "c" along with
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||||
rcu_read_lock_bh_held(). This is useful in code that
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||||
is invoked by both RCU-bh readers and updaters.
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||||
rcu_dereference_sched_check(p, c):
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||||
Use explicit check expression "c" along with
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rcu_read_lock_sched_held(). This is useful in code that
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is invoked by both RCU-sched readers and updaters.
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||||
srcu_dereference_check(p, c):
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Use explicit check expression "c" along with
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||||
srcu_read_lock_held()(). This is useful in code that
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is invoked by both SRCU readers and updaters.
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||||
rcu_dereference_index_check(p, c):
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||||
Use explicit check expression "c", but the caller
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must supply one of the rcu_read_lock_held() functions.
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This is useful in code that uses RCU-protected arrays
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that is invoked by both RCU readers and updaters.
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rcu_dereference_raw(p):
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Don't check. (Use sparingly, if at all.)
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rcu_dereference_protected(p, c):
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Use explicit check expression "c", and omit all barriers
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@@ -48,13 +66,11 @@ checking of rcu_dereference() primitives:
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value of the pointer itself, for example, against NULL.
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The rcu_dereference_check() check expression can be any boolean
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expression, but would normally include one of the rcu_read_lock_held()
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family of functions and a lockdep expression. However, any boolean
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expression can be used. For a moderately ornate example, consider
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the following:
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||||
expression, but would normally include a lockdep expression. However,
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any boolean expression can be used. For a moderately ornate example,
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consider the following:
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file = rcu_dereference_check(fdt->fd[fd],
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rcu_read_lock_held() ||
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lockdep_is_held(&files->file_lock) ||
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atomic_read(&files->count) == 1);
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@@ -62,7 +78,7 @@ This expression picks up the pointer "fdt->fd[fd]" in an RCU-safe manner,
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and, if CONFIG_PROVE_RCU is configured, verifies that this expression
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is used in:
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|
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1. An RCU read-side critical section, or
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1. An RCU read-side critical section (implicit), or
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2. with files->file_lock held, or
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3. on an unshared files_struct.
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@@ -42,7 +42,7 @@ fqs_holdoff Holdoff time (in microseconds) between consecutive calls
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fqs_stutter Wait time (in seconds) between consecutive bursts
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of calls to force_quiescent_state().
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||||
|
||||
irqreaders Says to invoke RCU readers from irq level. This is currently
|
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irqreader Says to invoke RCU readers from irq level. This is currently
|
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done via timers. Defaults to "1" for variants of RCU that
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permit this. (Or, more accurately, variants of RCU that do
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||||
-not- permit this know to ignore this variable.)
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||||
@@ -79,19 +79,68 @@ stutter The length of time to run the test before pausing for this
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||||
Specifying "stutter=0" causes the test to run continuously
|
||||
without pausing, which is the old default behavior.
|
||||
|
||||
test_boost Whether or not to test the ability of RCU to do priority
|
||||
boosting. Defaults to "test_boost=1", which performs
|
||||
RCU priority-inversion testing only if the selected
|
||||
RCU implementation supports priority boosting. Specifying
|
||||
"test_boost=0" never performs RCU priority-inversion
|
||||
testing. Specifying "test_boost=2" performs RCU
|
||||
priority-inversion testing even if the selected RCU
|
||||
implementation does not support RCU priority boosting,
|
||||
which can be used to test rcutorture's ability to
|
||||
carry out RCU priority-inversion testing.
|
||||
|
||||
test_boost_interval
|
||||
The number of seconds in an RCU priority-inversion test
|
||||
cycle. Defaults to "test_boost_interval=7". It is
|
||||
usually wise for this value to be relatively prime to
|
||||
the value selected for "stutter".
|
||||
|
||||
test_boost_duration
|
||||
The number of seconds to do RCU priority-inversion testing
|
||||
within any given "test_boost_interval". Defaults to
|
||||
"test_boost_duration=4".
|
||||
|
||||
test_no_idle_hz Whether or not to test the ability of RCU to operate in
|
||||
a kernel that disables the scheduling-clock interrupt to
|
||||
idle CPUs. Boolean parameter, "1" to test, "0" otherwise.
|
||||
Defaults to omitting this test.
|
||||
|
||||
torture_type The type of RCU to test: "rcu" for the rcu_read_lock() API,
|
||||
"rcu_sync" for rcu_read_lock() with synchronous reclamation,
|
||||
"rcu_bh" for the rcu_read_lock_bh() API, "rcu_bh_sync" for
|
||||
rcu_read_lock_bh() with synchronous reclamation, "srcu" for
|
||||
the "srcu_read_lock()" API, "sched" for the use of
|
||||
preempt_disable() together with synchronize_sched(),
|
||||
and "sched_expedited" for the use of preempt_disable()
|
||||
with synchronize_sched_expedited().
|
||||
torture_type The type of RCU to test, with string values as follows:
|
||||
|
||||
"rcu": rcu_read_lock(), rcu_read_unlock() and call_rcu().
|
||||
|
||||
"rcu_sync": rcu_read_lock(), rcu_read_unlock(), and
|
||||
synchronize_rcu().
|
||||
|
||||
"rcu_expedited": rcu_read_lock(), rcu_read_unlock(), and
|
||||
synchronize_rcu_expedited().
|
||||
|
||||
"rcu_bh": rcu_read_lock_bh(), rcu_read_unlock_bh(), and
|
||||
call_rcu_bh().
|
||||
|
||||
"rcu_bh_sync": rcu_read_lock_bh(), rcu_read_unlock_bh(),
|
||||
and synchronize_rcu_bh().
|
||||
|
||||
"rcu_bh_expedited": rcu_read_lock_bh(), rcu_read_unlock_bh(),
|
||||
and synchronize_rcu_bh_expedited().
|
||||
|
||||
"srcu": srcu_read_lock(), srcu_read_unlock() and
|
||||
synchronize_srcu().
|
||||
|
||||
"srcu_expedited": srcu_read_lock(), srcu_read_unlock() and
|
||||
synchronize_srcu_expedited().
|
||||
|
||||
"sched": preempt_disable(), preempt_enable(), and
|
||||
call_rcu_sched().
|
||||
|
||||
"sched_sync": preempt_disable(), preempt_enable(), and
|
||||
synchronize_sched().
|
||||
|
||||
"sched_expedited": preempt_disable(), preempt_enable(), and
|
||||
synchronize_sched_expedited().
|
||||
|
||||
Defaults to "rcu".
|
||||
|
||||
verbose Enable debug printk()s. Default is disabled.
|
||||
|
||||
@@ -100,12 +149,12 @@ OUTPUT
|
||||
|
||||
The statistics output is as follows:
|
||||
|
||||
rcu-torture: --- Start of test: nreaders=16 stat_interval=0 verbose=0
|
||||
rcu-torture: rtc: 0000000000000000 ver: 1916 tfle: 0 rta: 1916 rtaf: 0 rtf: 1915
|
||||
rcu-torture: Reader Pipe: 1466408 9747 0 0 0 0 0 0 0 0 0
|
||||
rcu-torture: Reader Batch: 1464477 11678 0 0 0 0 0 0 0 0
|
||||
rcu-torture: Free-Block Circulation: 1915 1915 1915 1915 1915 1915 1915 1915 1915 1915 0
|
||||
rcu-torture: --- End of test
|
||||
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: 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
|
||||
rcu-torture:--- End of test: SUCCESS: 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
|
||||
|
||||
The command "dmesg | grep torture:" will extract this information on
|
||||
most systems. On more esoteric configurations, it may be necessary to
|
||||
@@ -113,26 +162,55 @@ use other commands to access the output of the printk()s used by
|
||||
the RCU torture test. The printk()s use KERN_ALERT, so they should
|
||||
be evident. ;-)
|
||||
|
||||
The first and last lines show the rcutorture module parameters, and the
|
||||
last line shows either "SUCCESS" or "FAILURE", based on rcutorture's
|
||||
automatic determination as to whether RCU operated correctly.
|
||||
|
||||
The entries are as follows:
|
||||
|
||||
o "rtc": The hexadecimal address of the structure currently visible
|
||||
to readers.
|
||||
|
||||
o "ver": The number of times since boot that the rcutw writer task
|
||||
o "ver": The number of times since boot that the RCU writer task
|
||||
has changed the structure visible to readers.
|
||||
|
||||
o "tfle": If non-zero, indicates that the "torture freelist"
|
||||
containing structure to be placed into the "rtc" area is empty.
|
||||
containing structures to be placed into the "rtc" area is empty.
|
||||
This condition is important, since it can fool you into thinking
|
||||
that RCU is working when it is not. :-/
|
||||
|
||||
o "rta": Number of structures allocated from the torture freelist.
|
||||
|
||||
o "rtaf": Number of allocations from the torture freelist that have
|
||||
failed due to the list being empty.
|
||||
failed due to the list being empty. It is not unusual for this
|
||||
to be non-zero, but it is bad for it to be a large fraction of
|
||||
the value indicated by "rta".
|
||||
|
||||
o "rtf": Number of frees into the torture freelist.
|
||||
|
||||
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 "rtbke": rcutorture was unable to create the real-time kthreads
|
||||
used to force RCU priority inversion. This value should be zero.
|
||||
|
||||
o "rtbre": Although rcutorture successfully created the kthreads
|
||||
used to force RCU priority inversion, it was unable to set them
|
||||
to the real-time priority level of 1. This value should be zero.
|
||||
|
||||
o "rtbf": The number of times that RCU priority boosting failed
|
||||
to resolve RCU priority inversion.
|
||||
|
||||
o "rtb": The number of times that rcutorture attempted to force
|
||||
an RCU priority inversion condition. If you are testing RCU
|
||||
priority boosting via the "test_boost" module parameter, this
|
||||
value should be non-zero.
|
||||
|
||||
o "nt": The number of times rcutorture ran RCU read-side code from
|
||||
within a timer handler. This value should be non-zero only
|
||||
if you specified the "irqreader" module parameter.
|
||||
|
||||
o "Reader Pipe": Histogram of "ages" of structures seen by readers.
|
||||
If any entries past the first two are non-zero, RCU is broken.
|
||||
And rcutorture prints the error flag string "!!!" to make sure
|
||||
@@ -162,26 +240,15 @@ o "Free-Block Circulation": Shows the number of torture structures
|
||||
somehow gets incremented farther than it should.
|
||||
|
||||
Different implementations of RCU can provide implementation-specific
|
||||
additional information. For example, SRCU provides the following:
|
||||
additional information. For example, SRCU provides the following
|
||||
additional line:
|
||||
|
||||
srcu-torture: rtc: f8cf46a8 ver: 355 tfle: 0 rta: 356 rtaf: 0 rtf: 346 rtmbe: 0
|
||||
srcu-torture: Reader Pipe: 559738 939 0 0 0 0 0 0 0 0 0
|
||||
srcu-torture: Reader Batch: 560434 243 0 0 0 0 0 0 0 0
|
||||
srcu-torture: Free-Block Circulation: 355 354 353 352 351 350 349 348 347 346 0
|
||||
srcu-torture: per-CPU(idx=1): 0(0,1) 1(0,1) 2(0,0) 3(0,1)
|
||||
|
||||
The first four lines are similar to those for RCU. The last line shows
|
||||
the per-CPU counter state. The numbers in parentheses are the values
|
||||
of the "old" and "current" counters for the corresponding CPU. The
|
||||
"idx" value maps the "old" and "current" values to the underlying array,
|
||||
and is useful for debugging.
|
||||
|
||||
Similarly, sched_expedited RCU provides the following:
|
||||
|
||||
sched_expedited-torture: rtc: d0000000016c1880 ver: 1090796 tfle: 0 rta: 1090796 rtaf: 0 rtf: 1090787 rtmbe: 0 nt: 27713319
|
||||
sched_expedited-torture: Reader Pipe: 12660320201 95875 0 0 0 0 0 0 0 0 0
|
||||
sched_expedited-torture: Reader Batch: 12660424885 0 0 0 0 0 0 0 0 0 0
|
||||
sched_expedited-torture: Free-Block Circulation: 1090795 1090795 1090794 1090793 1090792 1090791 1090790 1090789 1090788 1090787 0
|
||||
This line shows the per-CPU counter state. The numbers in parentheses are
|
||||
the values of the "old" and "current" counters for the corresponding CPU.
|
||||
The "idx" value maps the "old" and "current" values to the underlying
|
||||
array, and is useful for debugging.
|
||||
|
||||
|
||||
USAGE
|
||||
|
||||
@@ -33,23 +33,23 @@ rcu/rcuboost:
|
||||
The output of "cat rcu/rcudata" looks as follows:
|
||||
|
||||
rcu_sched:
|
||||
0 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=545/1/0 df=50 of=0 ri=0 ql=163 qs=NRW. kt=0/W/0 ktl=ebc3 b=10 ci=153737 co=0 ca=0
|
||||
1 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=967/1/0 df=58 of=0 ri=0 ql=634 qs=NRW. kt=0/W/1 ktl=58c b=10 ci=191037 co=0 ca=0
|
||||
2 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1081/1/0 df=175 of=0 ri=0 ql=74 qs=N.W. kt=0/W/2 ktl=da94 b=10 ci=75991 co=0 ca=0
|
||||
3 c=20942 g=20943 pq=1 pqc=20942 qp=1 dt=1846/0/0 df=404 of=0 ri=0 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=72261 co=0 ca=0
|
||||
4 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=369/1/0 df=83 of=0 ri=0 ql=48 qs=N.W. kt=0/W/4 ktl=e0e7 b=10 ci=128365 co=0 ca=0
|
||||
5 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=381/1/0 df=64 of=0 ri=0 ql=169 qs=NRW. kt=0/W/5 ktl=fb2f b=10 ci=164360 co=0 ca=0
|
||||
6 c=20972 g=20973 pq=1 pqc=20972 qp=0 dt=1037/1/0 df=183 of=0 ri=0 ql=62 qs=N.W. kt=0/W/6 ktl=d2ad b=10 ci=65663 co=0 ca=0
|
||||
7 c=20897 g=20897 pq=1 pqc=20896 qp=0 dt=1572/0/0 df=382 of=0 ri=0 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=75006 co=0 ca=0
|
||||
0 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=545/1/0 df=50 of=0 ri=0 ql=163 qs=NRW. kt=0/W/0 ktl=ebc3 b=10 ci=153737 co=0 ca=0
|
||||
1 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=967/1/0 df=58 of=0 ri=0 ql=634 qs=NRW. kt=0/W/1 ktl=58c b=10 ci=191037 co=0 ca=0
|
||||
2 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=1081/1/0 df=175 of=0 ri=0 ql=74 qs=N.W. kt=0/W/2 ktl=da94 b=10 ci=75991 co=0 ca=0
|
||||
3 c=20942 g=20943 pq=1 pgp=20942 qp=1 dt=1846/0/0 df=404 of=0 ri=0 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=72261 co=0 ca=0
|
||||
4 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=369/1/0 df=83 of=0 ri=0 ql=48 qs=N.W. kt=0/W/4 ktl=e0e7 b=10 ci=128365 co=0 ca=0
|
||||
5 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=381/1/0 df=64 of=0 ri=0 ql=169 qs=NRW. kt=0/W/5 ktl=fb2f b=10 ci=164360 co=0 ca=0
|
||||
6 c=20972 g=20973 pq=1 pgp=20973 qp=0 dt=1037/1/0 df=183 of=0 ri=0 ql=62 qs=N.W. kt=0/W/6 ktl=d2ad b=10 ci=65663 co=0 ca=0
|
||||
7 c=20897 g=20897 pq=1 pgp=20896 qp=0 dt=1572/0/0 df=382 of=0 ri=0 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=75006 co=0 ca=0
|
||||
rcu_bh:
|
||||
0 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=545/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/0 ktl=ebc3 b=10 ci=0 co=0 ca=0
|
||||
1 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=967/1/0 df=3 of=0 ri=1 ql=0 qs=.... kt=0/W/1 ktl=58c b=10 ci=151 co=0 ca=0
|
||||
2 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1081/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/2 ktl=da94 b=10 ci=0 co=0 ca=0
|
||||
3 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1846/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=0 co=0 ca=0
|
||||
4 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=369/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/4 ktl=e0e7 b=10 ci=0 co=0 ca=0
|
||||
5 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=381/1/0 df=4 of=0 ri=1 ql=0 qs=.... kt=0/W/5 ktl=fb2f b=10 ci=0 co=0 ca=0
|
||||
6 c=1480 g=1480 pq=1 pqc=1479 qp=0 dt=1037/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/6 ktl=d2ad b=10 ci=0 co=0 ca=0
|
||||
7 c=1474 g=1474 pq=1 pqc=1473 qp=0 dt=1572/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=0 co=0 ca=0
|
||||
0 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=545/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/0 ktl=ebc3 b=10 ci=0 co=0 ca=0
|
||||
1 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=967/1/0 df=3 of=0 ri=1 ql=0 qs=.... kt=0/W/1 ktl=58c b=10 ci=151 co=0 ca=0
|
||||
2 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=1081/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/2 ktl=da94 b=10 ci=0 co=0 ca=0
|
||||
3 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=1846/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/3 ktl=d1cd b=10 ci=0 co=0 ca=0
|
||||
4 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=369/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/4 ktl=e0e7 b=10 ci=0 co=0 ca=0
|
||||
5 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=381/1/0 df=4 of=0 ri=1 ql=0 qs=.... kt=0/W/5 ktl=fb2f b=10 ci=0 co=0 ca=0
|
||||
6 c=1480 g=1480 pq=1 pgp=1480 qp=0 dt=1037/1/0 df=6 of=0 ri=1 ql=0 qs=.... kt=0/W/6 ktl=d2ad b=10 ci=0 co=0 ca=0
|
||||
7 c=1474 g=1474 pq=1 pgp=1473 qp=0 dt=1572/0/0 df=8 of=0 ri=1 ql=0 qs=.... kt=0/W/7 ktl=cf15 b=10 ci=0 co=0 ca=0
|
||||
|
||||
The first section lists the rcu_data structures for rcu_sched, the second
|
||||
for rcu_bh. Note that CONFIG_TREE_PREEMPT_RCU kernels will have an
|
||||
@@ -84,7 +84,7 @@ o "pq" indicates that this CPU has passed through a quiescent state
|
||||
CPU has not yet reported that fact, (2) some other CPU has not
|
||||
yet reported for this grace period, or (3) both.
|
||||
|
||||
o "pqc" indicates which grace period the last-observed quiescent
|
||||
o "pgp" indicates which grace period the last-observed quiescent
|
||||
state for this CPU corresponds to. This is important for handling
|
||||
the race between CPU 0 reporting an extended dynticks-idle
|
||||
quiescent state for CPU 1 and CPU 1 suddenly waking up and
|
||||
@@ -184,10 +184,14 @@ o "kt" is the per-CPU kernel-thread state. The digit preceding
|
||||
The number after the final slash is the CPU that the kthread
|
||||
is actually running on.
|
||||
|
||||
This field is displayed only for CONFIG_RCU_BOOST kernels.
|
||||
|
||||
o "ktl" is the low-order 16 bits (in hexadecimal) of the count of
|
||||
the number of times that this CPU's per-CPU kthread has gone
|
||||
through its loop servicing invoke_rcu_cpu_kthread() requests.
|
||||
|
||||
This field is displayed only for CONFIG_RCU_BOOST kernels.
|
||||
|
||||
o "b" is the batch limit for this CPU. If more than this number
|
||||
of RCU callbacks is ready to invoke, then the remainder will
|
||||
be deferred.
|
||||
|
||||
Reference in New Issue
Block a user