Date: Sat, 10 Jun 2017 20:41:53 +0000 (UTC) From: "George V. Neville-Neil" <gnn@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r319803 - head/share/man/man4 Message-ID: <201706102041.v5AKfrIv067402@repo.freebsd.org>
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Author: gnn Date: Sat Jun 10 20:41:53 2017 New Revision: 319803 URL: https://svnweb.freebsd.org/changeset/base/319803 Log: Manual page for the DTrace lockstat provider Reviewed by: markj MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D11128 Added: head/share/man/man4/dtrace_lockstat.4 (contents, props changed) Added: head/share/man/man4/dtrace_lockstat.4 ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/share/man/man4/dtrace_lockstat.4 Sat Jun 10 20:41:53 2017 (r319803) @@ -0,0 +1,251 @@ +.\" Copyright (c) 2017 George V. Neville-Neil <gnn@FreeBSD.org> +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.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 +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 +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 +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. +.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. +.Pp +The +.Fn lockstat:::adaptive-release +probe fires whenever an adaptive lock is released. +The only argument is a pointer to the lock structure which describes +the lock that is being released. +.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 +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 +.Fn lockstat:::spin-acquire +probe fires. +The only argument is a pointer to the lock structure which describes +the lock that is being acquired. +.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. +.Pp +The +.Fn lockstat:::spin-spin +probe fires when a thread stops spinning waiting for a spin mutex. +The first argument is a pointer to the lock structure that describes +the lock and the second argument is the length of the 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. +.Pp +The +.Fn lockstat:::rw-release +probe fires whenever a reader-writer lock is released. +.Pp +The +.Fn lockstat:::rw-block +probe fires whenever a thread removes itself from the CPU while +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 +trying to acquire a read lock, +otherwise it will be 0 indicating that we were spinning for the write lock. +The fourth argument is 1 if we were waiting for a reader to release the lock, +otherwise it will be 0 indicating that we were waiting for a writer +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 +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. +.Pp +The +.Fn lockstat:::rw-upgrade +probe fires whenever a thread tries to upgrade a lock from a +read lock to a write lock. +The only argument is a pointer to the structure which describes +the lock that is being acquired. +.Pp +.Fn lockstat:::rw-downgrade +probe fires whenever a thread tries downgrades a lock from a +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. +.Pp +Whenever a shared-exclusive lock is acquired the +.Fn lockstat:::sx-acquire +probe fires. +The only argument is a pointer to the structure which describes +the lock that is being acquired. +.Pp +The +.Fn lockstat:::sx-release +probe fires whenever an adaptive lock is released. +The only argument is a pointer to the lock structure which describes +the lock that is being released. +.Pp +The +.Fn lockstat:::sx-block +probe fires whenever a thread takes itself off the CPU while +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 +trying to acquire a read lock, +otherwise it will be 0 indicating that we were spinning for the write lock. +The fourth argument is 1 if we were waiting for a reader to release the lock, +otherwise it will be 0 indicating that we were waiting for a writer +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 +if the fourth argument is 1. +.Pp +The +.Fn lockstat:::sx-spin +probe fires when a thread takes itself off of the CPU while +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. +.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. +.Pp +The +.Fn lockstat:::sx-downgrade +probe fires whenever a thread downgrades a lock from a +shared-exclusive lock to a shared lock. +The only argument is a pointer to the structure which describes +the lock that is being downgraded. +.Pp +The +.Fn lockstat:::thread-spin +probe fires whenever a thread spins on a spin 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 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 +.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 .
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