diff options
Diffstat (limited to 'Documentation/RCU/Design/Data-Structures/Data-Structures.rst')
| -rw-r--r-- | Documentation/RCU/Design/Data-Structures/Data-Structures.rst | 28 |
1 files changed, 14 insertions, 14 deletions
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.rst b/Documentation/RCU/Design/Data-Structures/Data-Structures.rst index b34990c7c377..04e16775c752 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.rst +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.rst @@ -921,10 +921,10 @@ This portion of the ``rcu_data`` structure is declared as follows: :: - 1 int dynticks_snap; + 1 int watching_snap; 2 unsigned long dynticks_fqs; -The ``->dynticks_snap`` field is used to take a snapshot of the +The ``->watching_snap`` field is used to take a snapshot of the corresponding CPU's dyntick-idle state when forcing quiescent states, and is therefore accessed from other CPUs. Finally, the ``->dynticks_fqs`` field is used to count the number of times this CPU @@ -935,8 +935,8 @@ This portion of the rcu_data structure is declared as follows: :: - 1 long dynticks_nesting; - 2 long dynticks_nmi_nesting; + 1 long nesting; + 2 long nmi_nesting; 3 atomic_t dynticks; 4 bool rcu_need_heavy_qs; 5 bool rcu_urgent_qs; @@ -945,14 +945,14 @@ These fields in the rcu_data structure maintain the per-CPU dyntick-idle state for the corresponding CPU. The fields may be accessed only from the corresponding CPU (and from tracing) unless otherwise stated. -The ``->dynticks_nesting`` field counts the nesting depth of process +The ``->nesting`` field counts the nesting depth of process execution, so that in normal circumstances this counter has value zero or one. NMIs, irqs, and tracers are counted by the -``->dynticks_nmi_nesting`` field. Because NMIs cannot be masked, changes +``->nmi_nesting`` field. Because NMIs cannot be masked, changes to this variable have to be undertaken carefully using an algorithm provided by Andy Lutomirski. The initial transition from idle adds one, and nested transitions add two, so that a nesting level of five is -represented by a ``->dynticks_nmi_nesting`` value of nine. This counter +represented by a ``->nmi_nesting`` value of nine. This counter can therefore be thought of as counting the number of reasons why this CPU cannot be permitted to enter dyntick-idle mode, aside from process-level transitions. @@ -960,12 +960,12 @@ process-level transitions. However, it turns out that when running in non-idle kernel context, the Linux kernel is fully capable of entering interrupt handlers that never exit and perhaps also vice versa. Therefore, whenever the -``->dynticks_nesting`` field is incremented up from zero, the -``->dynticks_nmi_nesting`` field is set to a large positive number, and -whenever the ``->dynticks_nesting`` field is decremented down to zero, -the ``->dynticks_nmi_nesting`` field is set to zero. Assuming that +``->nesting`` field is incremented up from zero, the +``->nmi_nesting`` field is set to a large positive number, and +whenever the ``->nesting`` field is decremented down to zero, +the ``->nmi_nesting`` field is set to zero. Assuming that the number of misnested interrupts is not sufficient to overflow the -counter, this approach corrects the ``->dynticks_nmi_nesting`` field +counter, this approach corrects the ``->nmi_nesting`` field every time the corresponding CPU enters the idle loop from process context. @@ -992,8 +992,8 @@ code. +-----------------------------------------------------------------------+ | **Quick Quiz**: | +-----------------------------------------------------------------------+ -| Why not simply combine the ``->dynticks_nesting`` and | -| ``->dynticks_nmi_nesting`` counters into a single counter that just | +| Why not simply combine the ``->nesting`` and | +| ``->nmi_nesting`` counters into a single counter that just | | counts the number of reasons that the corresponding CPU is non-idle? | +-----------------------------------------------------------------------+ | **Answer**: | |