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epoch(9): Fix a few mandoc related issues

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- sections out of conventional order: Sh EXAMPLES
- sections out of conventional order: Sh SEE ALSO
- skipping end of block that is not open: El
This commit is contained in:
Gordon Bergling 2020-12-05 11:18:37 +00:00
parent 935b2ac1f1
commit 2f3e7fb2cc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=368368
1 changed files with 19 additions and 20 deletions
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39
share/man/man9/epoch.9
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@ -210,20 +210,6 @@ This function can sleep and is not optimized for performance.
.Sh RETURN VALUES
.Fn in_epoch curepoch
will return 1 if curthread is in curepoch, 0 otherwise.
.Sh CAVEATS
One must be cautious when using
.Fn epoch_wait_preempt .
Threads are pinned during epoch sections, so if a thread in a section is then
preempted by a higher priority compute bound thread on that CPU, it can be
prevented from leaving the section indefinitely.
.Pp
Epochs are not a straight replacement for read locks.
Callers must use safe list and tailq traversal routines in an epoch (see ck_queue).
When modifying a list referenced from an epoch section safe removal
routines must be used and the caller can no longer modify a list entry
in place.
An item to be modified must be handled with copy on write
and frees must be deferred until after a grace period has elapsed.
.Sh EXAMPLES
Async free example:
Thread 1:
@ -280,12 +266,6 @@ free would have to follow a call to
The
.Nm
kernel programming interface is under development and is subject to change.
.El
.Sh HISTORY
The
.Nm
framework first appeared in
.Fx 11.0 .
.Sh SEE ALSO
.Xr locking 9 ,
.Xr mtx_pool 9 ,
@ -295,3 +275,22 @@ framework first appeared in
.Xr sleep 9 ,
.Xr sx 9 ,
.Xr timeout 9
.Sh HISTORY
The
.Nm
framework first appeared in
.Fx 11.0 .
.Sh CAVEATS
One must be cautious when using
.Fn epoch_wait_preempt .
Threads are pinned during epoch sections, so if a thread in a section is then
preempted by a higher priority compute bound thread on that CPU, it can be
prevented from leaving the section indefinitely.
.Pp
Epochs are not a straight replacement for read locks.
Callers must use safe list and tailq traversal routines in an epoch (see ck_queue).
When modifying a list referenced from an epoch section safe removal
routines must be used and the caller can no longer modify a list entry
in place.
An item to be modified must be handled with copy on write
and frees must be deferred until after a grace period has elapsed.