PERFORCE change 145918 for review

[John Baldwin]

http://perforce.freebsd.org/chv.cgi?CH=145918

Change 145918 by jhb at jhb_mutex on 2008/07/25 21:01:26

	First cut at respecting cpusets in 4BSD.

Affected files ...

.. //depot/projects/smpng/sys/kern/sched_4bsd.c#75 edit

Differences ...

==== //depot/projects/smpng/sys/kern/sched_4bsd.c#75 (text+ko) ====

@@ -101,6 +101,9 @@
 #define SKE_RUNQ_PCPU(ts)						\
     ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq)
 
+#define	THREAD_CAN_SCHED(td, cpu)	\
+    CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
+
 static struct td_sched td_sched0;
 struct mtx sched_lock;
 
@@ -118,7 +121,8 @@
 static void	resetpriority(struct thread *td);
 static void	resetpriority_thread(struct thread *td);
 #ifdef SMP
-static int	forward_wakeup(int  cpunum);
+static int	sched_pickcpu(struct thread *td);
+static int	forward_wakeup(int cpunum);
 #endif
 
 static struct kproc_desc sched_kp = {
@@ -140,6 +144,7 @@
  * Per-CPU run queues
  */
 static struct runq runq_pcpu[MAXCPU];
+long runq_length[MAXCPU];
 #endif
 
 static void
@@ -1152,6 +1157,45 @@
 }
 #endif /* SMP */
 
+#ifdef SMP
+/*
+ * Find a CPU for this thread to run on.  If it can run on any CPU, then
+ * this returns NOCPU.
+ */
+static int
+sched_pickcpu(struct thread *td)
+{
+	int best, cpu, fullset;
+
+	mtx_assert(&sched_lock, MA_OWNED);
+
+	fullset = 1;
+	best = NOCPU;
+	for (cpu = 0; cpu <= mp_maxid; cpu++) {
+		if (CPU_ABSENT(cpu))
+			continue;
+		if (!THREAD_CAN_SCHED(td, cpu)) {
+			/*
+			 * At least one available CPU isn't in our
+			 * set, so it isn't a "full" set.
+			 */
+			fullset = 0;
+			continue;
+		}
+	
+		if (best == NOCPU)
+			best = cpu;
+		else if (runq_length[cpu] < runq_length[best])
+			best = cpu;
+	}
+
+	if (fullset)
+		return (NOCPU);
+	else
+		return (best);
+}
+#endif
+
 void
 sched_add(struct thread *td, int flags)
 #ifdef SMP
@@ -1195,11 +1239,18 @@
 		single_cpu = 1;
 		CTR3(KTR_RUNQ,
 		    "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, cpu);
-	} else {	
-		CTR2(KTR_RUNQ,
+	} else {
+		/* Find a valid CPU for our cpuset */
+		cpu = sched_pickcpu(td);
+		if (cpu == NOCPU) {
+			CTR2(KTR_RUNQ,
 		    "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts, td);
-		cpu = NOCPU;
-		ts->ts_runq = &runq;
+			ts->ts_runq = &runq;
+		} else {
+			single_cpu = 1;
+			CTR3(KTR_RUNQ,
+		    "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td, cpu);
+		}
 	}
 	
 	if (single_cpu && (cpu != PCPU_GET(cpuid))) {
@@ -1226,6 +1277,8 @@
 	if ((td->td_proc->p_flag & P_NOLOAD) == 0)
 		sched_load_add();
 	runq_add(ts->ts_runq, td, flags);
+	if (cpu != NOCPU)
+		runq_length[cpu]++;
 }
 #else /* SMP */
 {
@@ -1292,6 +1345,10 @@
 
 	if ((td->td_proc->p_flag & P_NOLOAD) == 0)
 		sched_load_rem();
+#ifdef SMP
+	if (ts->ts_runq != &runq)
+		runq_length[ts->ts_runq - runq_pcpu]--;
+#endif
 	runq_remove(ts->ts_runq, td);
 	TD_SET_CAN_RUN(td);
 }
@@ -1331,6 +1388,10 @@
 #endif
 
 	if (td) {
+#ifdef SMP
+		if (td == tdcpu)
+			runq_length[PCPU_GET(cpuid)]--;
+#endif
 		runq_remove(rq, td);
 		td->td_flags |= TDF_DIDRUN;
 
@@ -1515,4 +1576,17 @@
 void
 sched_affinity(struct thread *td)
 {
+#ifdef SMP
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+
+	/*
+	 * See if our current CPU is in the set.  If not, force a
+	 * context switch.
+	 */
+	if (THREAD_CAN_SCHED(td, PCPU_GET(cpuid)))
+		return;
+
+	mi_switch(SW_VOL, NULL);
+#endif
 }