svn commit: r217981 - stable/8/sys/kern

John Baldwin jhb at FreeBSD.org
Thu Jan 27 21:16:24 UTC 2011


Author: jhb
Date: Thu Jan 27 21:16:23 2011
New Revision: 217981
URL: http://svn.freebsd.org/changeset/base/217981

Log:
  MFC 217078,217079: Various priority fixes for creating new threads:
  - Move sched_fork() later in fork() after the various sections of the new
    thread and proc have been copied and zeroed from the old thread and
    proc.  Otherwise attempts to modify thread or process data in sched_fork()
    could be undone.
  - Don't copy td_{base,}_user_pri from the old thread to the new thread in
    sched_fork_thread() in ULE.  This is already done courtesy the bcopy()
    of the thread copy region.
  - Always initialize the real priority (td_priority) of new threads to the
    new thread's base priority (td_base_pri) to avoid bogusly inheriting a
    borrowed priority from the parent thread.
  - Properly initialize the base priority (td_base_pri) of thread0 to PVM
    to match the desired priority in td_priority.  Otherwise the first time
    thread0 used a borrowed priority it would drop down to PUSER instead of
    PVM.
  - Explicitly initialize the starting priority of new kprocs to PVM to
    avoid inheriting some random priority from thread0.

Modified:
  stable/8/sys/kern/init_main.c
  stable/8/sys/kern/kern_fork.c
  stable/8/sys/kern/kern_kthread.c
  stable/8/sys/kern/sched_4bsd.c
  stable/8/sys/kern/sched_ule.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)

Modified: stable/8/sys/kern/init_main.c
==============================================================================
--- stable/8/sys/kern/init_main.c	Thu Jan 27 20:53:03 2011	(r217980)
+++ stable/8/sys/kern/init_main.c	Thu Jan 27 21:16:23 2011	(r217981)
@@ -457,7 +457,7 @@ proc0_init(void *dummy __unused)
 	td->td_user_pri = PUSER;
 	td->td_base_user_pri = PUSER;
 	td->td_priority = PVM;
-	td->td_base_pri = PUSER;
+	td->td_base_pri = PVM;
 	td->td_oncpu = 0;
 	td->td_flags = TDF_INMEM|TDP_KTHREAD;
 	td->td_cpuset = cpuset_thread0();

Modified: stable/8/sys/kern/kern_fork.c
==============================================================================
--- stable/8/sys/kern/kern_fork.c	Thu Jan 27 20:53:03 2011	(r217980)
+++ stable/8/sys/kern/kern_fork.c	Thu Jan 27 21:16:23 2011	(r217981)
@@ -447,12 +447,6 @@ again:
 	p2 = newproc;
 	p2->p_state = PRS_NEW;		/* protect against others */
 	p2->p_pid = trypid;
-	/*
-	 * Allow the scheduler to initialize the child.
-	 */
-	thread_lock(td);
-	sched_fork(td, td2);
-	thread_unlock(td);
 	AUDIT_ARG_PID(p2->p_pid);
 	LIST_INSERT_HEAD(&allproc, p2, p_list);
 	LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
@@ -548,6 +542,13 @@ again:
 #endif
 
 	/*
+	 * Allow the scheduler to initialize the child.
+	 */
+	thread_lock(td);
+	sched_fork(td, td2);
+	thread_unlock(td);
+
+	/*
 	 * Duplicate sub-structures as needed.
 	 * Increase reference counts on shared objects.
 	 */

Modified: stable/8/sys/kern/kern_kthread.c
==============================================================================
--- stable/8/sys/kern/kern_kthread.c	Thu Jan 27 20:53:03 2011	(r217980)
+++ stable/8/sys/kern/kern_kthread.c	Thu Jan 27 21:16:23 2011	(r217981)
@@ -116,14 +116,15 @@ kproc_create(void (*func)(void *), void 
 
 	/* call the processes' main()... */
 	cpu_set_fork_handler(td, func, arg);
+	thread_lock(td);
 	TD_SET_CAN_RUN(td);
+	sched_prio(td, PVM);
+	sched_user_prio(td, PUSER);
 
 	/* Delay putting it on the run queue until now. */
-	if (!(flags & RFSTOPPED)) {
-		thread_lock(td);
+	if (!(flags & RFSTOPPED))
 		sched_add(td, SRQ_BORING); 
-		thread_unlock(td);
-	}
+	thread_unlock(td);
 
 	return 0;
 }

Modified: stable/8/sys/kern/sched_4bsd.c
==============================================================================
--- stable/8/sys/kern/sched_4bsd.c	Thu Jan 27 20:53:03 2011	(r217980)
+++ stable/8/sys/kern/sched_4bsd.c	Thu Jan 27 21:16:23 2011	(r217981)
@@ -748,6 +748,7 @@ sched_fork_thread(struct thread *td, str
 	childtd->td_estcpu = td->td_estcpu;
 	childtd->td_lock = &sched_lock;
 	childtd->td_cpuset = cpuset_ref(td->td_cpuset);
+	childtd->td_priority = childtd->td_base_pri;
 	ts = childtd->td_sched;
 	bzero(ts, sizeof(*ts));
 	ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY);

Modified: stable/8/sys/kern/sched_ule.c
==============================================================================
--- stable/8/sys/kern/sched_ule.c	Thu Jan 27 20:53:03 2011	(r217980)
+++ stable/8/sys/kern/sched_ule.c	Thu Jan 27 21:16:23 2011	(r217981)
@@ -1979,14 +1979,16 @@ sched_fork_thread(struct thread *td, str
 	ts2->ts_cpu = ts->ts_cpu;
 	ts2->ts_flags = 0;
 	/*
-	 * Grab our parents cpu estimation information and priority.
+	 * Grab our parents cpu estimation information.
 	 */
 	ts2->ts_ticks = ts->ts_ticks;
 	ts2->ts_ltick = ts->ts_ltick;
 	ts2->ts_incrtick = ts->ts_incrtick;
 	ts2->ts_ftick = ts->ts_ftick;
-	child->td_user_pri = td->td_user_pri;
-	child->td_base_user_pri = td->td_base_user_pri;
+	/*
+	 * Do not inherit any borrowed priority from the parent.
+	 */
+	child->td_priority = child->td_base_pri;
 	/*
 	 * And update interactivity score.
 	 */


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