Problems with O(1) scheduler on non-x86 arch's

James Bottomley (James.Bottomley@HansenPartnership.com)
Wed, 16 Jan 2002 21:29:48 -0500


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I've been on a bug hunting expedition to try to make the new scheduler work with the voyager architecture port in kernel 2.4.2. I'm not sure if this is a side effect of the port or an intentional architecture shift. Some of the architecture ports (mine included) store the physical cpu number in p->processor (now p->cpu) rather than the logical one. I'm not sure if shifting to logical cpu numbering was behind the name change or not, but anyway, in case this is merely an oversight, the attached patch fixes the problem for me.

James Bottomley
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Index: kernel/fork.c
===================================================================
RCS file: /home/jejb/CVSROOT/linux/2.5/kernel/fork.c,v
retrieving revision 1.1.1.5
diff -u -r1.1.1.5 fork.c
--- kernel/fork.c 16 Jan 2002 17:25:33 -0000 1.1.1.5
+++ kernel/fork.c 17 Jan 2002 02:18:29 -0000
@@ -650,7 +650,8 @@

/* ?? should we just memset this ?? */
for(i = 0; i < smp_num_cpus; i++)
- p->per_cpu_utime[i] = p->per_cpu_stime[i] = 0;
+ p->per_cpu_utime[cpu_logical_map(i)] =
+ p->per_cpu_stime[cpu_logical_map(i)] = 0;
spin_lock_init(&p->sigmask_lock);
}
#endif
Index: kernel/sched.c
===================================================================
RCS file: /home/jejb/CVSROOT/linux/2.5/kernel/sched.c,v
retrieving revision 1.1.1.4
diff -u -r1.1.1.4 sched.c
--- kernel/sched.c 16 Jan 2002 17:25:33 -0000 1.1.1.4
+++ kernel/sched.c 17 Jan 2002 02:18:29 -0000
@@ -267,7 +267,7 @@
unsigned long i, sum = 0;

for (i = 0; i < smp_num_cpus; i++)
- sum += cpu_rq(i)->nr_running;
+ sum += cpu_rq(cpu_logical_map(i))->nr_running;

return sum;
}
@@ -277,7 +277,7 @@
unsigned long i, sum = 0;

for (i = 0; i < smp_num_cpus; i++)
- sum += cpu_rq(i)->nr_switches;
+ sum += cpu_rq(cpu_logical_map(i))->nr_switches;

return sum;
}
@@ -287,7 +287,7 @@
unsigned long i, curr, max = 0;

for (i = 0; i < smp_num_cpus; i++) {
- curr = cpu_rq(i)->nr_running;
+ curr = cpu_rq(cpu_logical_map(i))->nr_running;
if (curr > max)
max = curr;
}
@@ -327,7 +327,7 @@
busiest = NULL;
max_load = 0;
for (i = 0; i < smp_num_cpus; i++) {
- rq_tmp = cpu_rq(i);
+ rq_tmp = cpu_rq(cpu_logical_map(i));
load = rq_tmp->nr_running;
if ((load > max_load) && (load < prev_max_load) &&
(rq_tmp != this_rq)) {

-
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