svn commit: r297273 - in head/sys: ddb kern sys

[Conrad E. Meyer]

Author: cem
Date: Fri Mar 25 19:35:29 2016
New Revision: 297273
URL: https://svnweb.freebsd.org/changeset/base/297273

Log:
  Add td_swinvoltick to track last involuntary context switch
  
  Expose in DDB via "show thread."
  
  Reviewed by:	markj
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/ddb/db_ps.c
  head/sys/kern/kern_synch.c
  head/sys/sys/proc.h

Modified: head/sys/ddb/db_ps.c
==============================================================================
--- head/sys/ddb/db_ps.c	Fri Mar 25 19:12:44 2016	(r297272)
+++ head/sys/ddb/db_ps.c	Fri Mar 25 19:35:29 2016	(r297273)
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/cons.h>
 #include <sys/jail.h>
 #include <sys/kdb.h>
+#include <sys/kernel.h>
 #include <sys/proc.h>
 #include <sys/sysent.h>
 #include <sys/systm.h>
@@ -302,6 +303,7 @@ DB_SHOW_COMMAND(thread, db_show_thread)
 	struct thread *td;
 	struct lock_object *lock;
 	bool comma;
+	int delta;
 
 	/* Determine which thread to examine. */
 	if (have_addr)
@@ -376,6 +378,16 @@ DB_SHOW_COMMAND(thread, db_show_thread)
 		    td->td_wchan);
 	db_printf(" priority: %d\n", td->td_priority);
 	db_printf(" container lock: %s (%p)\n", lock->lo_name, lock);
+	if (td->td_swvoltick != 0) {
+		delta = (u_int)ticks - (u_int)td->td_swvoltick;
+		db_printf(" last voluntary switch: %d ms ago\n",
+		    1000 * delta / hz);
+	}
+	if (td->td_swinvoltick != 0) {
+		delta = (u_int)ticks - (u_int)td->td_swinvoltick;
+		db_printf(" last involuntary switch: %d ms ago\n",
+		    1000 * delta / hz);
+	}
 }
 
 DB_SHOW_COMMAND(proc, db_show_proc)

Modified: head/sys/kern/kern_synch.c
==============================================================================
--- head/sys/kern/kern_synch.c	Fri Mar 25 19:12:44 2016	(r297272)
+++ head/sys/kern/kern_synch.c	Fri Mar 25 19:35:29 2016	(r297273)
@@ -438,8 +438,10 @@ mi_switch(int flags, struct thread *newt
 	if (flags & SW_VOL) {
 		td->td_ru.ru_nvcsw++;
 		td->td_swvoltick = ticks;
-	} else
+	} else {
 		td->td_ru.ru_nivcsw++;
+		td->td_swinvoltick = ticks;
+	}
 #ifdef SCHED_STATS
 	SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]);
 #endif

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h	Fri Mar 25 19:12:44 2016	(r297272)
+++ head/sys/sys/proc.h	Fri Mar 25 19:35:29 2016	(r297273)
@@ -254,6 +254,7 @@ struct thread {
 	int		td_slptick;	/* (t) Time at sleep. */
 	int		td_blktick;	/* (t) Time spent blocked. */
 	int		td_swvoltick;	/* (t) Time at last SW_VOL switch. */
+	int		td_swinvoltick;	/* (t) Time at last SW_INVOL switch. */
 	u_int		td_cow;		/* (*) Number of copy-on-write faults */
 	struct rusage	td_ru;		/* (t) rusage information. */
 	struct rusage_ext td_rux;	/* (t) Internal rusage information. */