Implement the DTrace sched provider. This implementation aims to be

compatible with the sched provider implemented by Solaris and its open-
source derivatives.  Full documentation of the sched provider can be found
on Oracle's DTrace wiki pages.

Note that for compatibility with scripts originally written for Solaris,
serveral probes are defined that will never fire.  These probes are defined
to fire when Solaris-specific features perform certain actions.  As these
features are not present in FreeBSD, the probes can never fire.

Also, I have added a two probes that are not defined in Solaris, lend-pri
and load-change.  These probes have been added to make it possible to
collect schedgraph data with DTrace.

Finally, a few probes are defined in Solaris to take a cpuinfo_t *
argument.  As it was not immediately clear to me how to translate that to
FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *.

Sponsored by: Sandvine Incorporated
MFC after:	2 weeks

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/kern/subr_turnstile.c b/sys/kern/subr_turnstile.c
index c3370db..76fb964 100644
--- a/sys/kern/subr_turnstile.c
+++ b/sys/kern/subr_turnstile.c
@@ -60,6 +60,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_ddb.h"
+#include "opt_kdtrace.h"
 #include "opt_turnstile_profiling.h"
 #include "opt_sched.h"
 
@@ -73,6 +74,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>
 #include <sys/queue.h>
 #include <sys/sched.h>
+#include <sys/sdt.h>
 #include <sys/sysctl.h>
 #include <sys/turnstile.h>
 
@@ -167,6 +169,11 @@ static void	turnstile_dtor(void *mem, int size, void *arg);
 static int	turnstile_init(void *mem, int size, int flags);
 static void	turnstile_fini(void *mem, int size);
 
+SDT_PROVIDER_DECLARE(sched);
+SDT_PROBE_DEFINE(sched, , , sleep, sleep);
+SDT_PROBE_DEFINE2(sched, , , wakeup, wakeup, "struct thread *", 
+    "struct proc *");
+
 /*
  * Walks the chain of turnstiles and their owners to propagate the priority
  * of the thread being blocked to all the threads holding locks that have to
@@ -740,6 +747,8 @@ turnstile_wait(struct turnstile *ts, struct thread *owner, int queue)
 		CTR4(KTR_LOCK, "%s: td %d blocked on [%p] %s", __func__,
 		    td->td_tid, lock, lock->lo_name);
 
+	SDT_PROBE0(sched, , , sleep);
+
 	THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
 	mi_switch(SW_VOL | SWT_TURNSTILE, NULL);
 
@@ -916,6 +925,7 @@ turnstile_unpend(struct turnstile *ts, int owner_type)
 	while (!TAILQ_EMPTY(&pending_threads)) {
 		td = TAILQ_FIRST(&pending_threads);
 		TAILQ_REMOVE(&pending_threads, td, td_lockq);
+		SDT_PROBE2(sched, , , wakeup, td, td->td_proc);
 		thread_lock(td);
 		THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
 		MPASS(td->td_proc->p_magic == P_MAGIC);