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Answer below.
On 09/05/2017 04:45 AM, Weichih Lu wrote:
Dear all,
I have a compute node with 64GB ram. And I set 50 hugepages wiht 1GB
hugepage size. I used command "free", it shows free memory is about
12GB. And free hugepages is 50.
Correct. By assigning hugepages, you use the memory allocated to the
hugepages.
Then I launch an instance with 16GB memory, set flavor tag
: hw:mem_page_size=large. It show Error: No valid host was found. There
are not enough hosts available.
Right, because you have only 12G of RAM available after
creating/allocating 50G out of your 64G.
Huge pages are entirely separate from the normal memory that a flavor
consumes. The 16GB memory in your flavor is RAM consumed on the host.
The huge pages are individual things that are consumed by the NUMA
topology that your instance will take. RAM != huge pages. Totally
different things.
And I check nova-scheduler log. My
compute is removed by RamFilter. I can launch an instance with 8GB
memory successfully, or I can launch an instance with 16GB memory
sucessfully by remove RamFilter.
That's because RamFilter doesn't deal with huge pages. Because huge
pages are a different resource than memory. The page itself is the resource.
The NUMATopologyFilter is the scheduler filter that evaluates the huge
page resources on a compute host and determines if the there are enough
*pages* available for the instance. Note that I say *pages* because the
unit of resource consumption for huge pages is not MB of RAM. It's a
single memory page.
Please read this excellent article by Steve Gordon for information on
what NUMA and huge pages are and how to use them in Nova:
http://redhatstackblog.redhat.com/2015/09/15/driving-in-the-fast-lane-huge-page-support-in-openstack-compute/
Best,
-jay
Does RamFilter only check free memory but not free hugepages?
How can I solve this problem?
I use openstack mitaka version.
thanks
WeiChih, Lu.
Best Regards.
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