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				.\" Copyright (c) 2017 George V. Neville-Neil <gnn@FreeBSD.org>
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				.Dd June 9, 2017
				.Dt DTRACE_LOCKSTAT 4
				.Os
				.Sh NAME
				.Nm dtrace_lockstat
				.Nd a DTrace provider for tracing CPU scheduling events
				.Sh SYNOPSIS
				.Fn lockstat:::adaptive-acquire "struct mtx *"
				.Fn lockstat:::adaptive-release "struct mtx *"
				.Fn lockstat:::adaptive-spin "struct mtx *" "uint64_t"
				.Fn lockstat:::adaptive-block "struct mtx *" "uint64_t"
				.Fn lockstat:::spin-acquire "struct mtx *"
				.Fn lockstat:::spin-release "struct mtx *"
				.Fn lockstat:::spin-spin "struct mtx *" "uint64_t"
				.Fn lockstat:::rw-acquire "struct rwlock *" "int"
				.Fn lockstat:::rw-release "struct rwlock *" "int"
				.Fn lockstat:::rw-block "struct rwlock *" "uint64_t" "int" "int" "int"
				.Fn lockstat:::rw-spin "struct rwlock *" "uint64_t"
				.Fn lockstat:::rw-upgrade "struct rwlock *"
				.Fn lockstat:::rw-downgrade "struct rwlock *"
				.Fn lockstat:::sx-acquire "struct sx *" "int"
				.Fn lockstat:::sx-release "struct sx *" "int"
				.Fn lockstat:::sx-block "struct sx *" "uint64_t" "int" "int" "int"
				.Fn lockstat:::sx-spin "struct sx *" "uint64_t"
				.Fn lockstat:::sx-upgrade "struct sx *"
				.Fn lockstat:::sx-downgrade "struct sx *"
				.Fn lockstat:::thread-spin "struct mtx *" "uint64"
				.Sh DESCRIPTION
				The DTrace
				.Nm lockstat
				wblockUnsubmitted Not Done Inline Actions .Nm is for setting the name of the thing documented by the man page. Normally, it is only set once at the beginning and then used without a value later. Here and later in this man page, it appears to be used for markup, but that's not really what it does. Depends on what you are trying to do, but probably should be a different macro. Maybe .Cm ? wblock: .Nm is for setting the name of the thing documented by the man page. Normally, it is only set…
				provider allows the tracing of events related to locking on FreeBSD.
				.Pp
				The
				.Nm lockstat
				provider contains DTrace probe for inspecting the kernel's lock
				wblockUnsubmitted Not Done Inline Actions Should this be "a DTrace probe" or "probes"? wblock: Should this be "a DTrace probe" or "probes"?
				state transitions.
				Tracepoints exist for several types of kernel
				locking primitives, including mutexes, spin, reader-writer,
				and shared exclusive locks.
				An attempt has been made to provide a regular and easy to understand
				wblockUnsubmitted Not Done Inline Actions This is a bit passive and implies that the attempt was not entirely successful. It's kind of implied that there was an attempt anyway. Also, not clear on what "regular" means in this context. How about just: The interface to the .Cm lockstat provider is simple and easy to understand. (See above about the .Cm, not sure if that's the right thing to use.) wblock: This is a bit passive and implies that the attempt was not entirely successful. It's kind of…
				interface to the
				.Nm lockstat
				provider.
				Each type of lock has an
				.Fn acquire
				and
				.Fn release
				probe which exposes the lock structure that is being operated upon.
				wblockUnsubmitted Not Done Inline Actions Suspect this would read better as "has acquire and release probes which expose", but it's a judgement call. wblock: Suspect this would read better as "has acquire and release probes which expose", but it's a…
				.Pp
				Whenever an MTX_DEF mutex is acquired the
				.Fn lockstat:::adaptive-acquire
				probe fires.
				The only argument is a pointer to the lock structure which describes
				the lock that is being acquired.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::adaptive-release
				probe fires whenever an adaptive lock is released.
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				The only argument is a pointer to the lock structure which describes
				the lock that is being released.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::adaptive-spin
				probe fires when an adaptive lock is acquired.
				The first argument is a pointer to the lock structure that describes
				the lock and the second argument is the amount of time,
				in nanoseconds,
				that the mutex spent spinning.
				.Pp
				The
				.Fn lockstat:::adaptive-block
				probe fires whenever thread takes itself off of the CPU
				wblockUnsubmitted Not Done Inline Actions s/whenever thread/when a thread/ wblock: s/whenever thread/when a thread/
				while trying to acquire the lock.
				The first argument is a pointer to the lock structure that describes
				the lock and the second argument is the length of time,
				in nanoseconds,
				that the waiting thread was blocked.
				The
				.Fn lockstat:::adaptive-block
				probe fires only after the lock has been successfully acquired,
				after the adaptive-acquire probe fires.
				.Pp
				Whenever a spin mutex is acquired the
				wblockUnsubmitted Not Done Inline Actions s/Whenever/When/ wblock: s/Whenever/When/
				.Fn lockstat:::spin-acquire
				probe fires.
				The only argument is a pointer to the lock structure which describes
				the lock that is being acquired.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::spin-release
				probe fires whenever a spin mutex is released.
				The only argument is a pointer to the lock structure which describes
				the lock that is being released.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::spin-spin
				probe fires when a thread stops spinning waiting for a spin mutex.
				wblockUnsubmitted Not Done Inline Actions s/waiting/while waiting/ wblock: s/waiting/while waiting/
				The first argument is a pointer to the lock structure that describes
				the lock and the second argument is the length of the time
				wblockUnsubmitted Not Done Inline Actions s/the time/time/ wblock: s/the time/time/
				spent spinning, in nanoseconds.
				.Pp
				Whenever a reader-writer lock is acquired the
				.Fn lockstat:::rw-acquire
				probe fires.
				The only argument is a pointer to the structure which describes
				the lock that is being acquired.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::rw-release
				probe fires whenever a reader-writer lock is released.
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				.Pp
				The
				.Fn lockstat:::rw-block
				probe fires whenever a thread removes itself from the CPU while
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				waiting to acquire the lock.
				The first argument is a pointer to the lock structure that describes
				the lock and the second argument is the length of time,
				in nanoseconds,
				that the waiting thread was blocked.
				The third argument is 1 if the thread was were spinning while
				wblockUnsubmitted Not Done Inline Actions s/were// wblock: s/were//
				trying to acquire a read lock,
				otherwise it will be 0 indicating that we were spinning for the write lock.
				wblockUnsubmitted Not Done Inline Actions s/we were/it was/ wblock: s/we were/it was/
				The fourth argument is 1 if we were waiting for a reader to release the lock,
				wblockUnsubmitted Not Done Inline Actions s/we were/it was/ wblock: s/we were/it was/
				otherwise it will be 0 indicating that we were waiting for a writer
				wblockUnsubmitted Not Done Inline Actions s/we were/it was/ wblock: s/we were/it was/
				to release the lock.
				The fifth argument is the number of readers that held the lock when
				we started spinning; in particular, argument 5 is non-zero only
				wblockUnsubmitted Not Done Inline Actions s/we/it/ Break the sentence instead of using a semicolon: it started spinning. In particular, argument 5 is non-zero only wblock: s/we/it/ Break the sentence instead of using a semicolon: ```it started spinning. In…
				if the fourth argument is 1.
				.Pp
				The
				.Fn lockstat:::rw-spin
				probe fires when a reader-writer lock takes itself off the CPU
				while waiting for the lock.
				The first argument is a pointer to the lock structure that describes
				the lock and the second argument returns an integer count of the
				number of spins that were completed.
				wblockUnsubmitted Not Done Inline Actions s/that were// wblock: s/that were//
				.Pp
				The
				.Fn lockstat:::rw-upgrade
				probe fires whenever a thread tries to upgrade a lock from a
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				read lock to a write lock.
				The only argument is a pointer to the structure which describes
				the lock that is being acquired.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				.Fn lockstat:::rw-downgrade
				probe fires whenever a thread tries downgrades a lock from a
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				read and write lock to a read lock.
				The only argument is a pointer to the structure which describes
				the lock that is being acquired.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				Whenever a shared-exclusive lock is acquired the
				wblockUnsubmitted Not Done Inline Actions s/Whenever/When/ Needs a comma, too: When a shared-exclusive lock is acquired, the That could be avoided by flipping the sentence: The .Fn lockstat:::sx-acquire probe fires when a shared-exclusive lock is acquired. wblock: s/Whenever/When/ Needs a comma, too: ```When a shared-exclusive lock is acquired, the``` That…
				.Fn lockstat:::sx-acquire
				probe fires.
				The only argument is a pointer to the structure which describes
				the lock that is being acquired.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::sx-release
				probe fires whenever an adaptive lock is released.
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				The only argument is a pointer to the lock structure which describes
				the lock that is being released.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::sx-block
				probe fires whenever a thread takes itself off the CPU while
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				waiting for the lock.
				The first argument is a pointer to the structure that describes
				the lock and the second argument is the length of time,
				in nanoseconds,
				that the waiting thread was blocked.
				The third argument is 1 if the thread was were spinning while
				wblockUnsubmitted Not Done Inline Actions s/was were/was/ wblock: s/was were/was/
				trying to acquire a read lock,
				otherwise it will be 0 indicating that we were spinning for the write lock.
				wblockUnsubmitted Not Done Inline Actions s/we were/it was/ wblock: s/we were/it was/
				The fourth argument is 1 if we were waiting for a reader to release the lock,
				wblockUnsubmitted Not Done Inline Actions s/we were/it was/ wblock: s/we were/it was/
				otherwise it will be 0 indicating that we were waiting for a writer
				wblockUnsubmitted Not Done Inline Actions There are two spaces before the zero. s/we were/it was/ wblock: There are two spaces before the zero. s/we were/it was/
				to release the lock.
				The fifth argument is the number of readers that held the lock when
				we started spinning; in particular, argument 5 is non-zero only
				wblockUnsubmitted Not Done Inline Actions s/we/it/ Copypasta for the semicolon, which are usually best reserved for types of writing other than documentation. Short, declarative sentences without pauses are best. wblock: s/we/it/ Copypasta for the semicolon, which are usually best reserved for types of writing…
				if the fourth argument is 1.
				.Pp
				The
				.Fn lockstat:::sx-spin
				probe fires when a thread takes itself off of the CPU while
				wblockUnsubmitted Not Done Inline Actions s/off of/off/ wblock: s/off of/off/
				waiting for the lock.
				The first argument is a pointer to the structure that describes
				the lock and the second argument returns an integer count of the
				number of spins that were completed.
				wblockUnsubmitted Not Done Inline Actions s/that were// wblock: s/that were//
				.Pp
				The
				.Fn lockstat:::sx-upgrade
				probe fires whenever a thread tries to upgrade a lock from a
				shared lock to a shared-exclusive lock.
				The only argument is a pointer to the structure which describes
				the lock that is being upgraded.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::sx-downgrade
				probe fires whenever a thread downgrades a lock from a
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				shared-exclusive lock to a shared lock.
				The only argument is a pointer to the structure which describes
				the lock that is being downgraded.
				wblockUnsubmitted Not Done Inline Actions s/that is// wblock: s/that is//
				.Pp
				The
				.Fn lockstat:::thread-spin
				probe fires whenever a thread spins on a spin lock.
				wblockUnsubmitted Not Done Inline Actions s/whenever/when/ wblock: s/whenever/when/
				The first argument is a pointer to the structure that describes
				the lock and the second argument is the length of time,
				in nanoseconds,
				that the thread was spinning.
				.Sh SEE ALSO
				.Xr dtrace 1 ,
				.Xr lockstat 1 ,
				.Xr locking 9 ,
				.Xr SDT 9 ,
				.Sh HISTORY
				The
				.Nm lockstat
				provider first appeared in OpenSolaris.
				The FreeBSD implementation of the
				wblockUnsubmitted Not Done Inline Actions Use .Fx for FreeBSD: The .Fx implementation of the .Cm lockstat (but see above, not sure about .Cm) wblock: Use .Fx for FreeBSD: ```The .Fx implementation of the .Cm lockstat``` (but see above, not sure…
				.Nm lockstat
				provider first appeared in
				.Fx 9.
				.Sh AUTHORS
				This manual page was written by
				.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org .