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membarrier.2: Some wording improvements 

I'll pass these to Mathieu Desnoyers for checking

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2018-04-12 13:25:56 +02:00
parent 13d4ca14fa
commit e8edc8917c
1 changed files with 16 additions and 12 deletions
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28
man2/membarrier.2
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@ -92,16 +92,18 @@ All threads on the system are targeted by this command.
Execute a memory barrier on all running threads of all processes that
previously registered with
.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED .
Upon return from the system call, the calling thread is ensured that all
Upon return from the system call, the calling thread has a guarantee that all
running threads have passed through a state where all memory accesses to
user-space addresses match program order between entry to and return
from the system call (non-running threads are de facto in such a state).
This covers only threads from processes which registered with
This guarantee is provided only for the threads of processes that
previously registered with
.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED .
Given that registration is about the intent to receive the barriers, it
is valid to invoke
.BR MEMBARRIER_CMD_GLOBAL_EXPEDITED
from a non-registered process.
from a process that has not employed
.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED .
.IP
The "expedited" commands complete faster than the non-expedited ones;
they never block, but have the downside of causing extra overhead.
@ -113,17 +115,18 @@ memory barriers.
.TP
.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED " (since Linux 4.14)"
Execute a memory barrier on each running thread belonging to the same
process as the current thread.
Upon return from system call, the calling
thread is assured that all its running threads siblings have passed
process as the calling thread.
Upon return from the system call, the calling
thread has a guarantee that all its running thread siblings have passed
through a state where all memory accesses to user-space addresses match
program order between entry to and return from the system call
(non-running threads are de facto in such a state).
This covers only threads from the same process as the calling thread.
This guarantee is provided only for threads in
the same process as the calling thread.
.IP
The "expedited" commands complete faster than the non-expedited ones;
they never block, but have the downside of causing extra overhead.
A process needs to register its intent to use the private
A process must register its intent to use the private
expedited command prior to using it.
.TP
.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED " (since Linux 4.14)"
@ -133,12 +136,13 @@ Register the process's intent to use
.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE " (since Linux 4.16)"
In addition to providing the memory ordering guarantees described in
.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED ,
ensure the calling thread, upon return from system call, that all its
running threads siblings have executed a core serializing instruction.
This only covers threads from the same process as the calling thread.
upon return from system call the calling thread has a guarantee that all its
running thread siblings have executed a core serializing instruction.
This guarantee is provided only for threads in
the same process as the calling thread.
The "expedited" commands complete faster than the non-expedited ones,
they never block, but have the downside of causing extra overhead.
A process needs to register its intent to use the private expedited sync
A process must register its intent to use the private expedited sync
core command prior to using it.
.TP
.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE " (since Linux 4.16)"