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Add lockmgr(9) probes to the lockstat DTrace provider.

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They follow the conventions set by rw and sx lock probes.  There is
an additional lockstat:::lockmgr-disown probe.

Update lockstat(1) to report on contention and hold events for
lockmgr locks.  Document the new probes in dtrace_lockstat.4, and
deduplicate some of the existing probe descriptions.

Reviewed by:	mjg
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D21355
This commit is contained in:
Mark Johnston 2019-08-21 23:43:58 +00:00
parent 81f666e79d
commit 5b699f1614
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=351361
5 changed files with 137 additions and 89 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
cddl/contrib/opensolaris/cmd/lockstat/lockstat.c
View File

@ -158,29 +158,33 @@ static ls_event_info_t g_event_info[LS_MAX_EVENTS] = {
{ 'C', "Lock", "R/W writer blocked by readers", "nsec",
"lockstat:::rw-block", "arg2 == 0 && arg3 == 0 && arg4" },
{ 'C', "Lock", "R/W reader blocked by writer", "nsec",
"lockstat:::rw-block", "arg2 != 0 && arg3 == 1" },
"lockstat:::rw-block", "arg2 == 1 && arg3 == 1" },
{ 'C', "Lock", "R/W reader blocked by write wanted", "nsec",
"lockstat:::rw-block", "arg2 != 0 && arg3 == 0 && arg4" },
"lockstat:::rw-block", "arg2 == 1 && arg3 == 0 && arg4" },
{ 'C', "Lock", "R/W writer spin on writer", "nsec",
"lockstat:::rw-spin", "arg2 == 0 && arg3 == 1" },
{ 'C', "Lock", "R/W writer spin on readers", "nsec",
"lockstat:::rw-spin", "arg2 == 0 && arg3 == 0 && arg4" },
{ 'C', "Lock", "R/W reader spin on writer", "nsec",
"lockstat:::rw-spin", "arg2 != 0 && arg3 == 1" },
"lockstat:::rw-spin", "arg2 == 1 && arg3 == 1" },
{ 'C', "Lock", "R/W reader spin on write wanted", "nsec",
"lockstat:::rw-spin", "arg2 != 0 && arg3 == 0 && arg4" },
"lockstat:::rw-spin", "arg2 == 1 && arg3 == 0 && arg4" },
{ 'C', "Lock", "SX exclusive block", "nsec",
"lockstat:::sx-block", "arg2 == 0" },
{ 'C', "Lock", "SX shared block", "nsec",
"lockstat:::sx-block", "arg2 != 0" },
"lockstat:::sx-block", "arg2 == 1" },
{ 'C', "Lock", "SX exclusive spin", "nsec",
"lockstat:::sx-spin", "arg2 == 0" },
{ 'C', "Lock", "SX shared spin", "nsec",
"lockstat:::sx-spin", "arg2 != 0" },
{ 'C', "Lock", "Unknown event (type 16)", "units" },
{ 'C', "Lock", "Unknown event (type 17)", "units" },
{ 'C', "Lock", "Unknown event (type 18)", "units" },
{ 'C', "Lock", "Unknown event (type 19)", "units" },
"lockstat:::sx-spin", "arg2 == 1" },
{ 'C', "Lock", "lockmgr writer blocked by writer", "nsec",
"lockstat:::lockmgr-block", "arg2 == 0 && arg3 == 1" },
{ 'C', "Lock", "lockmgr writer blocked by readers", "nsec",
"lockstat:::lockmgr-block", "arg2 == 0 && arg3 == 0 && arg4" },
{ 'C', "Lock", "lockmgr reader blocked by writer", "nsec",
"lockstat:::lockmgr-block", "arg2 == 1 && arg3 == 1" },
{ 'C', "Lock", "lockmgr reader blocked by write wanted", "nsec",
"lockstat:::lockmgr-block", "arg2 == 1 && arg3 == 0 && arg4" },
{ 'C', "Lock", "Unknown event (type 20)", "units" },
{ 'C', "Lock", "Unknown event (type 21)", "units" },
{ 'C', "Lock", "Unknown event (type 22)", "units" },

136
share/man/man4/dtrace_lockstat.4
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd March 2, 2018
.Dd August 20, 2019
.Dt DTRACE_LOCKSTAT 4
.Os
.Sh NAME
@ -50,6 +50,12 @@
.Fn lockstat:::sx-spin "struct sx *" "uint64_t"
.Fn lockstat:::sx-upgrade "struct sx *"
.Fn lockstat:::sx-downgrade "struct sx *"
.Fn lockstat:::lockmgr-acquire "struct lock *" "int"
.Fn lockstat:::lockmgr-release "struct lock *" "int"
.Fn lockstat:::lockmgr-disown "struct lock *" "int"
.Fn lockstat:::lockmgr-block "struct lock *" "uint64_t" "int" "int" "int"
.Fn lockstat:::lockmgr-upgrade "struct lock *"
.Fn lockstat:::lockmgr-downgrade "struct lock *"
.Fn lockstat:::thread-spin "struct mtx *" "uint64"
.Sh DESCRIPTION
The DTrace
@ -62,6 +68,7 @@ The
provider contains DTrace probes for inspecting kernel lock
state transitions.
Probes exist for the
.Xr lockmgr 9 ,
.Xr mutex 9 ,
.Xr rwlock 9 ,
and
@ -159,76 +166,50 @@ The second argument is
if the lock is being acquired or released as a writer, and
.Dv 1
if it is being acquired or released as a reader.
.Pp
The
.Fn lockstat:::rw-block
probe fires when a thread removes itself from the CPU while
waiting to acquire a
.Xr rwlock 9 .
The
.Fn lockstat:::rw-spin
probe fires when a thread spins while waiting to acquire a
.Xr rwlock 9 .
Both probes take the same set of arguments.
The first argument is a pointer to the lock structure that describes
the lock.
The second argument is the length of time, in nanoseconds,
that the waiting thread was off the CPU or spinning for the lock.
The third argument is
.Dv 0
if the thread is attempting to acquire the lock as a writer, and
.Dv 1
if the thread is attempting to acquire the lock as a reader.
The fourth argument is
.Dv 0
if the thread is waiting for a writer to release the lock, and
.Dv 1
if the thread is waiting for a reader to release the lock.
The fifth argument is the number of readers that held the lock when
the thread first attempted to acquire the lock.
This argument will be
.Dv 0
if the fourth argument is
.Dv 0 .
.Pp
The
.Fn lockstat:::rw-upgrade
probe fires when a thread successfully upgrades a held
.Xr rwlock 9
read lock to a write lock.
The
.Fn lockstat:::rw-downgrade
probe fires when a thread downgrades a held
.Xr rwlock 9
write lock to a read lock.
The only argument is a pointer to the structure which describes
the lock being acquired.
.Pp
The
.Fn lockstat:::sx-acquire
and
.Fn lockstat:::sx-release
probes fire when a
.Fn lockstat:::sx-release ,
and
.Fn lockstat:::lockmgr-acquire
and
.Fn lockstat:::lockmgr-release
probes fire upon the corresponding events for
.Xr sx 9
is acquired or released, respectively.
and
.Xr lockmgr 9
locks, respectively.
The
.Fn lockstat:::lockmgr-disown
probe fires when a
.Xr lockmgr 9
exclusive lock is disowned.
In this state, the lock remains exclusively held, but may be
released by a different thread.
The
.Fn lockstat:::lockmgr-release
probe does not fire when releasing a disowned lock.
The first argument is a pointer to the structure which describes
the lock being acquired.
the lock being disowned.
The second argument is
.Dv 0
if the shared lock is being acquired or released, and
.Dv 1
if the exclusive lock is being acquired or released.
.Dv 0 ,
for compatibility with
.Fn lockstat:::lockmgr-release .
.Pp
The
.Fn lockstat:::sx-block
probe fires when a thread takes itself off the CPU while
waiting to acquire a
.Xr sx 9 .
.Fn lockstat:::rw-block ,
.Fn lockstat:::sx-block ,
and
.Fn lockstat:::lockmgr-block
probes fire when a thread removes itself from the CPU while
waiting to acquire a lock of the corresponding type.
The
.Fn lockstat:::rw-spin
and
.Fn lockstat:::sx-spin
probe fires when a thread spins while waiting to acquire a
.Xr sx 9 .
Both probes take the same set of arguments.
probes fire when a thread spins while waiting to acquire a lock
of the corresponding type.
All probes take the same set of arguments.
The first argument is a pointer to the lock structure that describes
the lock.
The second argument is the length of time, in nanoseconds,
@ -240,28 +221,40 @@ if the thread is attempting to acquire the lock as a writer, and
if the thread is attempting to acquire the lock as a reader.
The fourth argument is
.Dv 0
if the thread is waiting for a writer to release the lock, and
if the thread is waiting for a reader to release the lock, and
.Dv 1
if the thread is waiting for a reader to release the lock.
if the thread is waiting for a writer to release the lock.
The fifth argument is the number of readers that held the lock when
the thread first attempted to acquire the lock.
This argument will be
.Dv 0
if the fourth argument is
.Dv 0 .
.Dv 1 .
.Pp
The
.Fn lockstat:::lockmgr-upgrade ,
.Fn lockstat:::rw-upgrade ,
and
.Fn lockstat:::sx-upgrade
probe fires when a thread successfully upgrades a held
probes fire when a thread successfully upgrades a held
.Xr lockmgr 9 ,
.Xr rwlock 9 ,
or
.Xr sx 9
shared lock to an exclusive lock.
shared/reader lock to an exclusive/writer lock.
The only argument is a pointer to the structure which describes
the lock being acquired.
The
.Fn lockstat:::lockmgr-downgrade ,
.Fn lockstat:::rw-downgrade ,
and
.Fn lockstat:::sx-downgrade
probe fires when a thread downgrades a held
probes fire when a thread downgrades a held
.Xr lockmgr 9 ,
.Xr rwlock 9 ,
or
.Xr sx 9
exclusive lock to a shared lock.
exclusive/writer lock to a shared/reader lock.
.Pp
The
.Fn lockstat:::thread-spin
@ -291,10 +284,11 @@ provider first appeared in
.Fx 9 .
.Sh AUTHORS
This manual page was written by
.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org .
.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org
and
.An -nosplit
.An Mark Johnston Aq Mt markj@FreeBSD.org .
.Sh BUGS
Probes for
.Xr lockmgr 9
and
.Xr rmlock 9
locks have not yet been added.

51
sys/kern/kern_lock.c
View File

@ -40,6 +40,7 @@ __FBSDID("$FreeBSD$");
#include <sys/lock.h>
#include <sys/lock_profile.h>
#include <sys/lockmgr.h>
#include <sys/lockstat.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sleepqueue.h>
@ -201,8 +202,8 @@ lockmgr_note_shared_acquire(struct lock *lk, int contested,
uint64_t waittime, const char *file, int line, int flags)
{
lock_profile_obtain_lock_success(&lk->lock_object, contested, waittime,
file, line);
LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(lockmgr__acquire, lk, contested,
waittime, file, line, LOCKSTAT_READER);
LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file, line);
WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file, line);
TD_LOCKS_INC(curthread);
@ -214,7 +215,7 @@ static void
lockmgr_note_shared_release(struct lock *lk, const char *file, int line)
{
lock_profile_release_lock(&lk->lock_object);
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk, LOCKSTAT_READER);
WITNESS_UNLOCK(&lk->lock_object, 0, file, line);
LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line);
TD_LOCKS_DEC(curthread);
@ -226,8 +227,8 @@ lockmgr_note_exclusive_acquire(struct lock *lk, int contested,
uint64_t waittime, const char *file, int line, int flags)
{
lock_profile_obtain_lock_success(&lk->lock_object, contested, waittime,
file, line);
LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(lockmgr__acquire, lk, contested,
waittime, file, line, LOCKSTAT_WRITER);
LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, lk->lk_recurse, file, line);
WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | LK_TRYWIT(flags), file,
line);
@ -239,7 +240,7 @@ static void
lockmgr_note_exclusive_release(struct lock *lk, const char *file, int line)
{
lock_profile_release_lock(&lk->lock_object);
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk, LOCKSTAT_WRITER);
LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, lk->lk_recurse, file,
line);
WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
@ -555,6 +556,9 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *iwmesg;
int ipri, itimo;
#ifdef KDTRACE_HOOKS
uint64_t sleep_time = 0;
#endif
#ifdef LOCK_PROFILING
uint64_t waittime = 0;
int contested = 0;
@ -645,8 +649,14 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
* shared lock and the shared waiters flag is set,
* we will sleep.
*/
#ifdef KDTRACE_HOOKS
sleep_time -= lockstat_nsecs(&lk->lock_object);
#endif
error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
SQ_SHARED_QUEUE);
#ifdef KDTRACE_HOOKS
sleep_time += lockstat_nsecs(&lk->lock_object);
#endif
flags &= ~LK_INTERLOCK;
if (error) {
LOCK_LOG3(lk,
@ -658,6 +668,12 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
__func__, lk);
}
if (error == 0) {
#ifdef KDTRACE_HOOKS
if (sleep_time != 0)
LOCKSTAT_RECORD4(lockmgr__block, lk, sleep_time,
LOCKSTAT_READER, (x & LK_SHARE) == 0,
(x & LK_SHARE) == 0 ? 0 : LK_SHARERS(x));
#endif
#ifdef LOCK_PROFILING
lockmgr_note_shared_acquire(lk, contested, waittime,
file, line, flags);
@ -682,6 +698,9 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
const char *iwmesg;
int ipri, itimo;
#ifdef KDTRACE_HOOKS
uint64_t sleep_time = 0;
#endif
#ifdef LOCK_PROFILING
uint64_t waittime = 0;
int contested = 0;
@ -821,8 +840,14 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
* exclusive lock and the exclusive waiters flag
* is set, we will sleep.
*/
#ifdef KDTRACE_HOOKS
sleep_time -= lockstat_nsecs(&lk->lock_object);
#endif
error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
SQ_EXCLUSIVE_QUEUE);
#ifdef KDTRACE_HOOKS
sleep_time += lockstat_nsecs(&lk->lock_object);
#endif
flags &= ~LK_INTERLOCK;
if (error) {
LOCK_LOG3(lk,
@ -834,6 +859,12 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
__func__, lk);
}
if (error == 0) {
#ifdef KDTRACE_HOOKS
if (sleep_time != 0)
LOCKSTAT_RECORD4(lockmgr__block, lk, sleep_time,
LOCKSTAT_WRITER, (x & LK_SHARE) == 0,
(x & LK_SHARE) == 0 ? 0 : LK_SHARERS(x));
#endif
#ifdef LOCK_PROFILING
lockmgr_note_exclusive_acquire(lk, contested, waittime,
file, line, flags);
@ -877,6 +908,7 @@ lockmgr_upgrade(struct lock *lk, u_int flags, struct lock_object *ilk,
line);
WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE |
LK_TRYWIT(flags), file, line);
LOCKSTAT_RECORD0(lockmgr__upgrade, lk);
TD_SLOCKS_DEC(curthread);
goto out;
}
@ -1024,7 +1056,8 @@ lockmgr_xunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_obje
goto out;
}
if (tid != LK_KERNPROC)
lock_profile_release_lock(&lk->lock_object);
LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk,
LOCKSTAT_WRITER);
if (x == tid && atomic_cmpset_rel_ptr(&lk->lk_lock, tid, LK_UNLOCKED))
goto out;
@ -1205,7 +1238,6 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
break;
case LK_DOWNGRADE:
_lockmgr_assert(lk, KA_XLOCKED, file, line);
LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line);
/*
@ -1231,6 +1263,8 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
break;
cpu_spinwait();
}
LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
LOCKSTAT_RECORD0(lockmgr__downgrade, lk);
break;
case LK_RELEASE:
_lockmgr_assert(lk, KA_LOCKED, file, line);
@ -1462,6 +1496,7 @@ _lockmgr_disown(struct lock *lk, const char *file, int line)
if (LK_HOLDER(lk->lk_lock) != tid)
return;
lock_profile_release_lock(&lk->lock_object);
LOCKSTAT_RECORD1(lockmgr__disown, lk, LOCKSTAT_WRITER);
LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
TD_LOCKS_DEC(curthread);

8
sys/kern/kern_lockstat.c
View File

@ -62,6 +62,14 @@ SDT_PROBE_DEFINE2(lockstat, , , sx__spin, "struct sx *", "uint64_t");
SDT_PROBE_DEFINE1(lockstat, , , sx__upgrade, "struct sx *");
SDT_PROBE_DEFINE1(lockstat, , , sx__downgrade, "struct sx *");
SDT_PROBE_DEFINE2(lockstat, , , lockmgr__acquire, "struct lock *", "int");
SDT_PROBE_DEFINE2(lockstat, , , lockmgr__release, "struct lock *", "int");
SDT_PROBE_DEFINE2(lockstat, , , lockmgr__disown, "struct lock *", "int");
SDT_PROBE_DEFINE5(lockstat, , , lockmgr__block, "struct lock *", "uint64_t",
"int", "int", "int");
SDT_PROBE_DEFINE1(lockstat, , , lockmgr__upgrade, "struct lock *");
SDT_PROBE_DEFINE1(lockstat, , , lockmgr__downgrade, "struct lock *");
SDT_PROBE_DEFINE2(lockstat, , , thread__spin, "struct mtx *", "uint64_t");
volatile bool __read_frequently lockstat_enabled;

7
sys/sys/lockstat.h
View File

@ -65,6 +65,13 @@ SDT_PROBE_DECLARE(lockstat, , , sx__spin);
SDT_PROBE_DECLARE(lockstat, , , sx__upgrade);
SDT_PROBE_DECLARE(lockstat, , , sx__downgrade);
SDT_PROBE_DECLARE(lockstat, , , lockmgr__acquire);
SDT_PROBE_DECLARE(lockstat, , , lockmgr__release);
SDT_PROBE_DECLARE(lockstat, , , lockmgr__disown);
SDT_PROBE_DECLARE(lockstat, , , lockmgr__block);
SDT_PROBE_DECLARE(lockstat, , , lockmgr__upgrade);
SDT_PROBE_DECLARE(lockstat, , , lockmgr__downgrade);
SDT_PROBE_DECLARE(lockstat, , , thread__spin);
#define LOCKSTAT_WRITER 0