diff options
Diffstat (limited to 'Documentation/RCU')
| -rw-r--r-- | Documentation/RCU/checklist.txt | 6 | ||||
| -rw-r--r-- | Documentation/RCU/torture.txt | 6 | ||||
| -rw-r--r-- | Documentation/RCU/whatisRCU.txt | 22 |
3 files changed, 7 insertions, 27 deletions
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index 79e789b8b8ea..7703ec73a9bb 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -354,12 +354,6 @@ over a rather long period of time, but improvements are always welcome! using RCU rather than SRCU, because RCU is almost always faster and easier to use than is SRCU. - If you need to enter your read-side critical section in a - hardirq or exception handler, and then exit that same read-side - critical section in the task that was interrupted, then you need - to srcu_read_lock_raw() and srcu_read_unlock_raw(), which avoid - the lockdep checking that would otherwise this practice illegal. - Also unlike other forms of RCU, explicit initialization and cleanup is required via init_srcu_struct() and cleanup_srcu_struct(). These are passed a "struct srcu_struct" diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt index 7dce8a17eac2..d8a502387397 100644 --- a/Documentation/RCU/torture.txt +++ b/Documentation/RCU/torture.txt @@ -182,12 +182,6 @@ torture_type The type of RCU to test, with string values as follows: "srcu_expedited": srcu_read_lock(), srcu_read_unlock() and synchronize_srcu_expedited(). - "srcu_raw": srcu_read_lock_raw(), srcu_read_unlock_raw(), - and call_srcu(). - - "srcu_raw_sync": srcu_read_lock_raw(), srcu_read_unlock_raw(), - and synchronize_srcu(). - "sched": preempt_disable(), preempt_enable(), and call_rcu_sched(). diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 10df0b82f459..0f0fb7c432c2 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -842,9 +842,7 @@ SRCU: Critical sections Grace period Barrier srcu_read_lock synchronize_srcu srcu_barrier srcu_read_unlock call_srcu - srcu_read_lock_raw synchronize_srcu_expedited - srcu_read_unlock_raw - srcu_dereference + srcu_dereference synchronize_srcu_expedited SRCU: Initialization/cleanup init_srcu_struct @@ -865,38 +863,32 @@ list can be helpful: a. Will readers need to block? If so, you need SRCU. -b. Is it necessary to start a read-side critical section in a - hardirq handler or exception handler, and then to complete - this read-side critical section in the task that was - interrupted? If so, you need SRCU's srcu_read_lock_raw() and - srcu_read_unlock_raw() primitives. - -c. What about the -rt patchset? If readers would need to block +b. What about the -rt patchset? If readers would need to block in an non-rt kernel, you need SRCU. If readers would block in a -rt kernel, but not in a non-rt kernel, SRCU is not necessary. -d. Do you need to treat NMI handlers, hardirq handlers, +c. Do you need to treat NMI handlers, hardirq handlers, and code segments with preemption disabled (whether via preempt_disable(), local_irq_save(), local_bh_disable(), or some other mechanism) as if they were explicit RCU readers? If so, RCU-sched is the only choice that will work for you. -e. Do you need RCU grace periods to complete even in the face +d. Do you need RCU grace periods to complete even in the face of softirq monopolization of one or more of the CPUs? For example, is your code subject to network-based denial-of-service attacks? If so, you need RCU-bh. -f. Is your workload too update-intensive for normal use of +e. Is your workload too update-intensive for normal use of RCU, but inappropriate for other synchronization mechanisms? If so, consider SLAB_DESTROY_BY_RCU. But please be careful! -g. Do you need read-side critical sections that are respected +f. Do you need read-side critical sections that are respected even though they are in the middle of the idle loop, during user-mode execution, or on an offlined CPU? If so, SRCU is the only choice that will work for you. -h. Otherwise, use RCU. +g. Otherwise, use RCU. Of course, this all assumes that you have determined that RCU is in fact the right tool for your job. |