Hi Vasilis,
Sorry for the delay and thank you for reviewing and testing. :)
On 05/03/2013 06:50 PM, Vasilis Liaskovitis wrote:
Should we skip ranges on nodes that the kernel uses? e.g. with
if (memblock_is_kernel_node(nid))
continue;
Yes. I think I forgot to call it in this patch.
Will update in the next version.
- I am getting a "PANIC: early exception" when rebooting with movablecore=acpi
after hotplugging memory on node0 or node1 of a 2-node VM. The guest kernel is
based on
git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git
for-x86-mm (e9058baf) + these v2 patches.
This happens with or without the above memblock_is_kernel_node(nid) check.
Perhaps I am missing something or I need a newer "ACPI, numa: Parse numa info
early" patch-set?
I didn't test it on a VM. But on my real box, I haven't got a panic
when rebooting. I think I can help to test it in a VM, but would you
please to
tell me how to setup a environment as yours ?
A general question: Disabling hot-pluggability/zone-movable eligibility for a
whole node sounds a bit inflexible, if the machine only has one node to begin
with. Would it be possible to keep movable information per SRAT entry? I.e
if the BIOS presents multiple SRAT entries for one node/PXM (say node 0), and
there is no memblock/kernel allocation on one of these SRAT entries, could
we still mark this SRAT entry's range as hot-pluggable/movable? Not sure if
many real machine BIOSes would do this, but seabios could. This implies that
SRAT entries are processed for movable-zone eligilibity before they are merged
on node/PXM basis entry-granularity (I think numa_cleanup_meminfo currently does
this merge).
Yes, this can be done. But in real usage, part of the memory in a node
is hot-removable makes no sense, I think. We cannot remove the whole node,
so we cannot remove a real hardware device.
But in virtualization, would you please give a reason why we need this
entry-granularity ?
Another thinking. Assume I didn't understand your question correctly. :)
Now in kernel, we can recognize a node (by PXM in SRAT), but we cannot
recognize a memory device. Are you saying if we have this
entry-granularity,
we can hotplug a single memory device in a node ? (Perhaps there are more
than on memory device in a node.)
If so, it makes sense. But I don't the kernel is able to recognize which
device a memory range belongs to now. And I'm not sure if we can do this.
Of course the kernel should still have enough memory(i.e. non movable zone) to
boot. Can we ensure that at least certain amount of memory is non-movable, and
then, given more separate SRAT entries for node0 not used by kernel, treat
these rest entries as movable?
I tried this idea before. But as HPA said, it seems no way to calculate
how much
memory the kernel needs.
https://lkml.org/lkml/2012/11/27/29
Thanks. :)
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