Jes Sorensen wrote:
On 06/24/10 13:34, Andre Przywara wrote:
Avi Kivity wrote:
On 06/24/2010 01:58 PM, Andre Przywara wrote:
Non-anonymous memory doesn't work well with ksm and transparent
hugepages. Is it possible to use anonymous memory rather than file
backed?
I'd prefer non-file backed, too. But that is how the current huge pages
implementation is done. We could use MAP_HUGETLB and declare NUMA _and_
huge pages as 2.6.32+ only. Unfortunately I didn't find an easy way to
detect the presence of the MAP_HUGETLB flag. If the kernel does not
support it, it seems that mmap silently ignores it and uses 4KB pages
instead.
Bit behind on the mailing list, but I think this look very promising.
I really think it makes more sense to make QEMU aware of the NUMA setup
as well, rather than relying on numctl to do the work outside.
One thing you need to consider is what happens with migration once a
user specifies -numa. IMHO it is acceptable to simply disable migration
for the given guest.
Is that really a problem? You create the guest on the target with a NUMA
setup specific to the target machine. That could mean that you pin
multiple guest nodes to the same host node, but that shouldn't break
something, right? The guest part can (and should be!) migrated along
with all the other device state. I think this is still missing from the
current implementation.
Cheers,
Jes
PS: Are you planning on submitting anything to Linux Plumbers Conference
about this? :)
Yes, I was planning to submit a proposal, as I saw NUMA mentioned in the
topics list. AFAIK the deadline is July 19th, right? That gives me
another week after my vacation (for which I leave in a few minutes).
Regards,
Andre.
--
Andre Przywara
AMD-OSRC (Dresden)
Tel: x29712
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