diff options
| -rw-r--r-- | share/man/man9/rmlock.9 | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/share/man/man9/rmlock.9 b/share/man/man9/rmlock.9 index fd420cfbf3a8c..1be822be340cb 100644 --- a/share/man/man9/rmlock.9 +++ b/share/man/man9/rmlock.9 @@ -39,7 +39,7 @@ .Nm rm_wunlock , .Nm rm_wowned , .Nm RM_SYSINIT -.Nd mostly read lock - a kernel reader/writer lock optimized for mostly read access patterns +.Nd kernel reader/writer lock optimized for mostly read access patterns .Sh SYNOPSIS .In sys/param.h .In sys/lock.h @@ -91,7 +91,8 @@ can be locked while holding a non-spin mutex, and an cannot be held while sleeping. The .Nm -locks have full priority propagation like mutexes. The +locks have full priority propagation like mutexes. +The .Va rm_priotracker structure argument supplied in .Fn rm_rlock @@ -113,19 +114,22 @@ as mostly reader lock, described by Optionally allowing readers to recurse by setting .Dv LO_RECURSABLE in -.Fa opts +.Fa opts . The name description is used solely for debugging purposes. This function must be called before any other operations on the lock. -.It Fn rm_rlock "struct rmlock *rm" "struct rm_priotracker* tracker" +.It Fn rm_rlock "struct rmlock *rm" "struct rm_priotracker* tracker" Lock .Fa rm -as a reader. Using +as a reader. +Using .Fa tracker to track read owners of a lock for priority propagation. This data structure is only used internally by .Nm -and must persist until rm_runlock has been called. +and must persist until +.Fn rm_runlock +has been called. This data structure can be allocated on the stack since rmlocks cannot be held while sleeping. If any thread holds this lock exclusively, the current thread blocks, @@ -147,7 +151,7 @@ If there are any shared owners of the lock, the current thread blocks. The .Fn rm_wlock function cannot be called recursively. -.It Fn rm_runlock "struct rmlock *rm" "struct rm_priotracker* tracker" +.It Fn rm_runlock "struct rmlock *rm" "struct rm_priotracker* tracker" This function releases a shared lock previously acquired by .Fn rm_rlock . The @@ -169,12 +173,11 @@ This function returns a non-zero value if the current thread owns an exclusive lock on .Fa rm . .El -.El .Sh SEE ALSO .Xr locking 9 , .Xr mutex 9 , .Xr panic 9 , -.Xr rwlock 9, +.Xr rwlock 9 , .Xr sema 9 , .Xr sx 9 .Sh HISTORY @@ -192,16 +195,15 @@ This manual page was written by for rwlock and modified to reflect rmlock by .An "Stephan Uphoff" . .Sh BUGS -.Pp The .Nm implementation is currently not optimized for single processor systems. .Pp The .Nm -implementation uses a single per cpu list shared by all +implementation uses a single per CPU list shared by all rmlocks in the system. -If rmlocks become popular, hashing to multiple per cpu queues may +If rmlocks become popular, hashing to multiple per CPU queues may be needed to speed up the writer lock process. .Pp The |