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Diffstat (limited to 'Documentation/RCU/Design/Requirements/Requirements.html')
| -rw-r--r-- | Documentation/RCU/Design/Requirements/Requirements.html | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html index 62e847bcdcdd..49690228b1c6 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.html +++ b/Documentation/RCU/Design/Requirements/Requirements.html @@ -581,7 +581,8 @@ This guarantee was only partially premeditated. DYNIX/ptx used an explicit memory barrier for publication, but had nothing resembling <tt>rcu_dereference()</tt> for subscription, nor did it have anything resembling the <tt>smp_read_barrier_depends()</tt> -that was later subsumed into <tt>rcu_dereference()</tt>. +that was later subsumed into <tt>rcu_dereference()</tt> and later +still into <tt>READ_ONCE()</tt>. The need for these operations made itself known quite suddenly at a late-1990s meeting with the DEC Alpha architects, back in the days when DEC was still a free-standing company. @@ -2797,7 +2798,7 @@ 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 +3129,7 @@ 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. |