Messages in this thread | | | Date | Thu, 21 Apr 2011 08:04:17 +0200 | From | Andreas Herrmann <> | Subject | Re: Linux 2.6.39-rc4 (regression: NUMA on multi-node CPUs broken) |
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On Thu, Apr 21, 2011 at 11:04:27AM +0900, KOSAKI Motohiro wrote: > > Following patch breaks real NUMA on multi-node CPUs like AMD > > Magny-Cours and should be reverted (or changed to just take effect in > > case of numa=fake): > > > > commit 7d6b46707f2491a94f4bd3b4329d2d7f809e9368 > > Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > > Date: Fri Apr 15 20:39:01 2011 +0900 > > > > x86, NUMA: Fix fakenuma boot failure > > > > ... > > > > Thus, this patch implements a reassignment of node-ids if buggy firmware > > or numa emulation makes wrong cpu node map. Tt enforce all logical cpus > > in the same physical cpu share the same node. > > > > ... > > > > +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 assumes all logical cpus in the same physical cpu > > + * share the same node. But, buggy ACPI or NUMA emulation might assign > > + * them to different node. Fix it. > > + */ > > > > ... > > > > This is a false assumption. Magny-Cours has two nodes in the same > > physical package. The scheduler was (kind of) fixed to work around > > this boot problem for multi-node CPUs (with 2.6.32). > > I agree we have to fix this ASAP. I also think we have to avoid reintroduce > the same again. Can you please tell me the commit-id of this one?
It's
commit 5a925b4282d7f805deafde62001a83dbaf8be275 Author: Andreas Herrmann <andreas.herrmann3@amd.com> Date: Thu Sep 3 09:44:28 2009 +0200
x86, sched: Workaround broken sched domain creation for AMD Magny-Cours
> > If this is also > > an issue with wrong cpu node maps in case of NUMA emulation this might > > be fixed similar or this quirk should only be applied in case of NUMA > > emulation. > > Indeed. > > Tejun, Do you remember I sent numa emulation specific patch at first. now > I'm beside with Andreas. Because I bet current numa fallback code (you > pointed out one) has no user. > > Or, please let us know if you have an alternative patch. > > Attached revert and fakenuma spefic fix patches.
Andreas
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