[patch] migration thread & hotplug fixes, 2.5.23

From: Ingo Molnar (mingo@elte.hu)
Date: Wed Jun 19 2002 - 03:38:46 EST


the attached patch fixes the migration init code to deal with nonlinear
enumeration of CPUs.

        Ingo

diff -Nru a/kernel/sched.c b/kernel/sched.c
--- a/kernel/sched.c Wed Jun 19 10:35:55 2002
+++ b/kernel/sched.c Wed Jun 19 10:35:55 2002
@@ -1775,6 +1775,8 @@
         preempt_enable();
 }
 
+static __initdata int master_migration_thread;
+
 static int migration_thread(void * bind_cpu)
 {
         int cpu = (int) (long) bind_cpu;
@@ -1786,14 +1788,12 @@
         sigfillset(&current->blocked);
         set_fs(KERNEL_DS);
 
- /* FIXME: First CPU may not be zero, but this crap code
- vanishes with hotplug cpu patch anyway. --RR */
         /*
- * The first migration thread is started on CPU #0. This one can
- * migrate the other migration threads to their destination CPUs.
+ * The first migration thread is started on CPU #0, it migrates
+ * the other migration threads to their destination CPUs.
          */
- if (cpu != 0) {
- while (!cpu_rq(0)->migration_thread)
+ if (cpu != master_migration_thread) {
+ while (!cpu_rq(master_migration_thread)->migration_thread)
                         yield();
                 set_cpus_allowed(current, 1UL << cpu);
         }
@@ -1857,7 +1857,9 @@
 {
         int cpu;
 
- current->cpus_allowed = 1UL << 0;
+ master_migration_thread = smp_processor_id();
+ current->cpus_allowed = 1UL << master_migration_thread;
+
         for (cpu = 0; cpu < NR_CPUS; cpu++) {
                 if (!cpu_online(cpu))
                         continue;

-
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