On 09/06/2017 01:21 AM, Weichih Lu wrote:
Thanks for your response.
Is this mean if I want to create an instance with flavor: 16G memory
(hw:mem_page_size=large), I need to preserve memory more than 16GB ?
This instance consume hugepages resource.
You need to reserve fewer 1GB huge pages than 50 if you want to launch a
16GB instance on a host with 64GB of RAM. Try reserving 32 1GB huge pages.
Best,
-jay
2017-09-06 1:47 GMT+08:00 Jay Pipes <jaypi...@gmail.com
<mailto:jaypi...@gmail.com>>:
Please remember to add a topic [nova] marker to your subject line.
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/
<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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