Andre Przywara wrote:
Hi,
this patch series introduces multiple NUMA nodes support within KVM
guests.
This will improve the performance of guests which are bigger than one
node (number of VCPUs and/or amount of memory) and also allows better
balancing by taking better usage of each node's memory.
It also improves the one node case by pinning a guest to this node and
avoiding access of remote memory from one VCPU.
Could you please post this to qemu-devel? There's really nothing KVM
specific here.
The user (or better: management application) specifies the host nodes
the guest should use: -nodes 2,3 would create a two node guest mapped to
node 2 and 3 on the host. These numbers are handed over to libnuma:
VCPUs are pinned to the nodes and the allocated guest memory is bound to
it's respective node. Since libnuma seems not to be installed
everywhere, the user has to enable this via configure --enable-numa
In the BIOS code an ACPI SRAT table was added, which describes the NUMA
topology to the guest. The number of nodes is communicated via the CMOS
RAM (offset 0x3E). If someone thinks of this as a bad idea, tell me.
I think the dependency on libnuma is a bad idea. It's mixing a
mechanism (emulating NUMA layout) with a policy (how to do memory/VCPU
placement).
If you split the NUMA emulation bits into a separate patch series, that
has no dependency on the host NUMA topology, I think we look at the
existing mechanisms we have to see if they're sufficient to do static
placement on NUMA boundaries. vcpu pinning is easy enough, I think the
only place we're lacking is memory layout. Note, that's totally
independent of the guest's NUMA characteristics though. You may still
want half of memory to be pinned between two nodes even if the guest has
no SRAT tables.
Regards,
Anthony Liguori
To take use of the new BIOS, install the iasl compiler
(http://acpica.org/downloads/) and type "make bios" before installing,
so the default BIOS will be replaced with the modified one.
Node over-committing is allowed (-nodes 0,0,0,0), omitting the -nodes
parameter reverts to the old behavior.
Please apply.
Regards,
Andre.
Patch 1/3: introduce a command line parameter
Patch 2/3: allocate guests resources from different host nodes
Patch 3/3: generate an appropriate SRAT ACPI table
Signed-off-by: Andre Przywara <[EMAIL PROTECTED]>
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