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Subject[PATCH v2] x86-64, NUMA: fix fakenuma boot failure
Date
Hi

> Hello,
>
> On Wed, Apr 13, 2011 at 04:02:43PM +0900, KOSAKI Motohiro wrote:
> > Your patch have two mistake.
> >
> > 1) link_thread_siblings() is for HT
> > set_cpu_sibling_map() has another sibling calculations.
> > 2) numa_set_node() is not enough. scheduler is using node_to_cpumask_map[] too.
>
> Thanks for seeing this through but your patch is badly whitespace
> broken. Can you please check your mail setup and repost? Also, some
> comments below.

hmm...
My carbon copy is not corrupted. Maybe crappy intermediate server override it?


> > btw, Please see cpu_coregroup_mask(). its return value depend on
> > sched_mc_power_savings and sched_smt_power_savings. then, we need to care
> > both cpu_core_mask and cpu_llc_shared_mask. I think.
>
> Hmmmm....
>
> > +static void __cpuinit node_cpumap_same_phys(int cpu1, int cpu2)
>
> What does the "phys" mean? Maybe something like
> check_cpu_siblings_on_same_node() is a better name?

ok, will fix.


>
> > + /*
> > + * Our CPU scheduler assume all cpus in the same physical cpu package
> > + * are assigned the same node. But, Buggy ACPI table or NUMA emulation
> > + * might assigne them to different node. Fix it.
> typo

Grr. thank you.

>
> > + */
> > + if (node1 != node2) {
> > + pr_warning("CPU %d in node %d and CPU %d in node %d are in the same physical CPU. forcing same node %d\n",
> > + cpu1, node1, cpu2, node2, node2);
> > +
> > + numa_set_node(cpu1, node2);
> > + cpumask_set_cpu(cpu1, node_to_cpumask_map[node2]);
> > + cpumask_clear_cpu(cpu1, node_to_cpumask_map[node1]);
>
> Maybe what you want is the following?
>
> numa_remove_cpu(cpu1);
> numa_set_node(cpu1, node2)
> numa_add_cpu(cpu1)

Right. That's better.


From 1b7868de51941f39699c08f0d6ab429cd9db15bf Mon Sep 17 00:00:00 2001
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Wed, 13 Apr 2011 15:47:12 +0900
Subject: [PATCH] x86-64, NUMA: fix fakenuma boot failure

Currently, numa=fake boot parameter is broken. If it's used, kernel
doesn't boot and makes panic by zero divide error.

Call Trace:
[<ffffffff8104ad4c>] find_busiest_group+0x38c/0xd30
[<ffffffff81086aff>] ? local_clock+0x6f/0x80
[<ffffffff81050533>] load_balance+0xa3/0x600
[<ffffffff81050f53>] idle_balance+0xf3/0x180
[<ffffffff81550092>] schedule+0x722/0x7d0
[<ffffffff81550538>] ? wait_for_common+0x128/0x190
[<ffffffff81550a65>] schedule_timeout+0x265/0x320
[<ffffffff81095815>] ? lock_release_holdtime+0x35/0x1a0
[<ffffffff81550538>] ? wait_for_common+0x128/0x190
[<ffffffff8109bb6c>] ? __lock_release+0x9c/0x1d0
[<ffffffff815534e0>] ? _raw_spin_unlock_irq+0x30/0x40
[<ffffffff815534e0>] ? _raw_spin_unlock_irq+0x30/0x40
[<ffffffff81550540>] wait_for_common+0x130/0x190
[<ffffffff81051920>] ? try_to_wake_up+0x510/0x510
[<ffffffff8155067d>] wait_for_completion+0x1d/0x20
[<ffffffff8107f36c>] kthread_create_on_node+0xac/0x150
[<ffffffff81077bb0>] ? process_scheduled_works+0x40/0x40
[<ffffffff8155045f>] ? wait_for_common+0x4f/0x190
[<ffffffff8107a283>] __alloc_workqueue_key+0x1a3/0x590
[<ffffffff81e0cce2>] cpuset_init_smp+0x6b/0x7b
[<ffffffff81df3d07>] kernel_init+0xc3/0x182
[<ffffffff8155d5e4>] kernel_thread_helper+0x4/0x10
[<ffffffff81553cd4>] ? retint_restore_args+0x13/0x13
[<ffffffff81df3c44>] ? start_kernel+0x400/0x400
[<ffffffff8155d5e0>] ? gs_change+0x13/0x13
The zero divede is caused following line. (ie group->cpu_power==0)

update_sg_lb_stats()
/* Adjust by relative CPU power of the group */
sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) /
group->cpu_power;
This is regression since commit e23bba6044 (x86-64, NUMA: Unify
emulated distance mapping). Because It drop fake_physnodes() and
then cpu-node mapping was changed.

old) all cpus are assinged node 0
now) cpus are assigned round robin
(the logic is implemented by numa_init_array())

Why round robin assignment doesn't work? Because init_numa_sched_groups_power()
assume all logical cpus in the same physical cpu are assigned the same node.
(Then it only account group_first_cpu()). But the simple round robin
broke the above assumption.

Thus, this patch implement to reassigne node-id if buggy firmware or numa
emulation makes wrong cpu node map.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shaohui Zheng <shaohui.zheng@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@linux.intel.com>
---
arch/x86/kernel/smpboot.c | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index c2871d3..78c422d 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -312,6 +312,26 @@ void __cpuinit smp_store_cpu_info(int id)
identify_secondary_cpu(c);
}

+static void __cpuinit check_cpu_siblings_on_same_node(int cpu1, int cpu2)
+{
+ int node1 = early_cpu_to_node(cpu1);
+ int node2 = early_cpu_to_node(cpu2);
+
+ /*
+ * Our CPU scheduler assume all logical cpus in the same physical cpu
+ * package are assigned the same node. But, Buggy ACPI table or NUMA
+ * emulation might assign them to different node. Fix it.
+ */
+ if (node1 != node2) {
+ pr_warning("CPU %d in node %d and CPU %d in node %d are in the same physical CPU. forcing same node %d\n",
+ cpu1, node1, cpu2, node2, node2);
+
+ numa_remove_cpu(cpu1);
+ numa_set_node(cpu1, node2);
+ numa_add_cpu(cpu1);
+ }
+}
+
static void __cpuinit link_thread_siblings(int cpu1, int cpu2)
{
cpumask_set_cpu(cpu1, cpu_sibling_mask(cpu2));
@@ -320,6 +340,7 @@ static void __cpuinit link_thread_siblings(int cpu1, int cpu2)
cpumask_set_cpu(cpu2, cpu_core_mask(cpu1));
cpumask_set_cpu(cpu1, cpu_llc_shared_mask(cpu2));
cpumask_set_cpu(cpu2, cpu_llc_shared_mask(cpu1));
+ check_cpu_siblings_on_same_node(cpu1, cpu2);
}


@@ -361,10 +382,12 @@ void __cpuinit set_cpu_sibling_map(int cpu)
per_cpu(cpu_llc_id, cpu) == per_cpu(cpu_llc_id, i)) {
cpumask_set_cpu(i, cpu_llc_shared_mask(cpu));
cpumask_set_cpu(cpu, cpu_llc_shared_mask(i));
+ check_cpu_siblings_on_same_node(cpu, i);
}
if (c->phys_proc_id == cpu_data(i).phys_proc_id) {
cpumask_set_cpu(i, cpu_core_mask(cpu));
cpumask_set_cpu(cpu, cpu_core_mask(i));
+ check_cpu_siblings_on_same_node(cpu, i);
/*
* Does this new cpu bringup a new core?
*/
--
1.7.3.1






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