#. `Other RCU Flavors`_
#. `Possible Future Changes`_
-This is followed by a `summary <#Summary>`__, however, the answers to
+This is followed by a summary_, however, the answers to
each quick quiz immediately follows the quiz. Select the big white space
with your mouse to see the answer.
| case, voluntary context switch) within an RCU read-side critical |
| section. However, sleeping locks may be used within userspace RCU |
| read-side critical sections, and also within Linux-kernel sleepable |
-| RCU `(SRCU) <#Sleepable%20RCU>`__ read-side critical sections. In |
+| RCU `(SRCU) <Sleepable RCU_>`__ read-side critical sections. In |
| addition, the -rt patchset turns spinlocks into a sleeping locks so |
| that the corresponding critical sections can be preempted, which also |
| means that these sleeplockified spinlocks (but not other sleeping |
RCU <https://lore.kernel.org/r/20090113221724.GA15307@linux.vnet.ibm.com>`__
was born. Josh Triplett has since taken over the small-memory banner
with his `Linux kernel tinification <https://tiny.wiki.kernel.org/>`__
-project, which resulted in `SRCU <#Sleepable%20RCU>`__ becoming optional
+project, which resulted in `SRCU <Sleepable RCU_>`__ becoming optional
for those kernels not needing it.
The remaining performance requirements are, for the most part,
the relevant Kconfig options and kernel boot parameters. RCU currently
does not do much sanity checking of these parameters, so please use
caution when changing them. Note that these forward-progress measures
-are provided only for RCU, not for `SRCU <#Sleepable%20RCU>`__ or `Tasks
-RCU <#Tasks%20RCU>`__.
+are provided only for RCU, not for `SRCU <Sleepable RCU_>`__ or `Tasks
+RCU`_.
RCU takes the following steps in call_rcu() to encourage timely
invocation of callbacks when any given non-\ ``rcu_nocbs`` CPU has
Again, these are default values when running at ``HZ=1000``, and can be
overridden. Again, these forward-progress measures are provided only for
-RCU, not for `SRCU <#Sleepable%20RCU>`__ or `Tasks
-RCU <#Tasks%20RCU>`__. Even for RCU, callback-invocation forward
+RCU, not for `SRCU <Sleepable RCU_>`__ or `Tasks
+RCU`_. Even for RCU, callback-invocation forward
progress for ``rcu_nocbs`` CPUs is much less well-developed, in part
because workloads benefiting from ``rcu_nocbs`` CPUs tend to invoke
call_rcu() relatively infrequently. If workloads emerge that need
The Linux kernel supports CPU hotplug, which means that CPUs can come
and go. It is of course illegal to use any RCU API member from an
-offline CPU, with the exception of `SRCU <#Sleepable%20RCU>`__ read-side
+offline CPU, with the exception of `SRCU <Sleepable RCU_>`__ read-side
critical sections. This requirement was present from day one in
DYNIX/ptx, but on the other hand, the Linux kernel's CPU-hotplug
implementation is “interesting.”
However, RCU must be reliably informed as to whether any given CPU is
currently in the idle loop, and, for ``NO_HZ_FULL``, also whether that
CPU is executing in usermode, as discussed
-`earlier <#Energy%20Efficiency>`__. It also requires that the
+`earlier <Energy Efficiency_>`__. It also requires that the
scheduling-clock interrupt be enabled when RCU needs it to be:
#. If a CPU is either idle or executing in usermode, and RCU believes it
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Expanding on the `earlier
-discussion <#Performance%20and%20Scalability>`__, RCU is used heavily by
+discussion <Performance and Scalability_>`__, RCU is used heavily by
hot code paths in performance-critical portions of the Linux kernel's
networking, security, virtualization, and scheduling code paths. RCU
must therefore use efficient implementations, especially in its
projects / thirdparty / kernel / linux.git / blobdiff