diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-10-24 18:42:41 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-12-04 21:28:59 +0300 |
| commit | f2b1760aedba1d8394636ba31b9e864e82527528 (patch) | |
| tree | d56f3cf3d669e9ffa8e1c57926e8772fc4ce6559 /Documentation/RCU | |
| parent | 388a4c88064e7e62602b4d92ca127f0b0c9b305a (diff) | |
| download | linux-f2b1760aedba1d8394636ba31b9e864e82527528.tar.xz | |
doc: Eliminate cond_resched_rcu_qs() in favor of cond_resched()
Now that cond_resched() also provides RCU quiescent states when
needed, it can be used in place of cond_resched_rcu_qs(). This
commit therefore documents this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/RCU')
| -rw-r--r-- | Documentation/RCU/Design/Data-Structures/Data-Structures.html | 3 | ||||
| -rw-r--r-- | Documentation/RCU/Design/Requirements/Requirements.html | 4 | ||||
| -rw-r--r-- | Documentation/RCU/stallwarn.txt | 10 |
3 files changed, 8 insertions, 9 deletions
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index 38d6d800761f..412466e4967a 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html @@ -1097,7 +1097,8 @@ will cause the CPU to disregard the values of its counters on its next exit from idle. Finally, the <tt>rcu_qs_ctr_snap</tt> field is used to detect cases where a given operation has resulted in a quiescent state -for all flavors of RCU, for example, <tt>cond_resched_rcu_qs()</tt>. +for all flavors of RCU, for example, <tt>cond_resched()</tt> +when RCU has indicated a need for quiescent states. <h5>RCU Callback Handling</h5> diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html index 62e847bcdcdd..0372e6c54eef 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.html +++ b/Documentation/RCU/Design/Requirements/Requirements.html @@ -2797,7 +2797,7 @@ RCU must avoid degrading real-time response for CPU-bound threads, whether executing in usermode (which is one use case for <tt>CONFIG_NO_HZ_FULL=y</tt>) or in the kernel. That said, CPU-bound loops in the kernel must execute -<tt>cond_resched_rcu_qs()</tt> at least once per few tens of milliseconds +<tt>cond_resched()</tt> at least once per few tens of milliseconds in order to avoid receiving an IPI from RCU. <p> @@ -3128,7 +3128,7 @@ The solution, in the form of is to have implicit read-side critical sections that are delimited by voluntary context switches, that is, calls to <tt>schedule()</tt>, -<tt>cond_resched_rcu_qs()</tt>, and +<tt>cond_resched()</tt>, and <tt>synchronize_rcu_tasks()</tt>. In addition, transitions to and from userspace execution also delimit tasks-RCU read-side critical sections. diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index a08f928c8557..4259f95c3261 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -23,12 +23,10 @@ o A CPU looping with preemption disabled. This condition can o A CPU looping with bottom halves disabled. This condition can result in RCU-sched and RCU-bh stalls. -o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the - kernel without invoking schedule(). Note that cond_resched() - does not necessarily prevent RCU CPU stall warnings. Therefore, - if the looping in the kernel is really expected and desirable - behavior, you might need to replace some of the cond_resched() - calls with calls to cond_resched_rcu_qs(). +o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the kernel + without invoking schedule(). If the looping in the kernel is + really expected and desirable behavior, you might need to add + some calls to cond_resched(). o Booting Linux using a console connection that is too slow to keep up with the boot-time console-message rate. For example, |