On 02/06/2022 15:00, Ilya Maximets wrote:
On 6/2/22 13:01, Kevin Traynor wrote:
On 01/06/2022 14:30, David Marchand wrote:
On Wed, May 25, 2022 at 1:11 PM Kevin Traynor <ktray...@redhat.com> wrote:
Currently mempools for vhost are being assigned before the vhost device
is added. In some cases this may be just reusing an existing mempool but
in others it can require creation of a mempool.
For multi-NUMA, the NUMA info of the vhost port is not known until a
device is added to the port, so on multi-NUMA systems the initial NUMA
node for the mempool is a best guess based on vswitchd affinity.
When a device is added to the vhost port, the NUMA info can be checked
and if the guess was incorrect a mempool on the correct NUMA node
created.
For multi-NUMA, the current scheme can have the effect of creating a
mempool on a NUMA node that will not be needed and at least for a certain
time period requires more memory on a NUMA node.
It is also difficult for a user trying to provision memory on different
NUMA nodes, if they are not sure which NUMA node the initial mempool
for a vhost port will be on.
For single NUMA, even though the mempool will be on the correct NUMA, it
is assigned ahead of time and if a vhost device was not added, it could
also be using uneeded memory.
This patch delays the creation of the mempool for a vhost port until the
vhost device is added.
Signed-off-by: Kevin Traynor <ktray...@redhat.com>
Reviewed-by: David Marchand <david.march...@redhat.com>
Thanks for aligning the behavior, and updating the commitlog.
I did not test the mono numa part but I guess you did, and I don't see
what could be wrong.
I just wonder if we should add some note in NEWS for this change of
behavior, though it is really low-level/internal...
Regardless of the update on NEWS, this version lgtm.
Thanks David. I don't mind about the NEWS. It is a low-level change, but it
might help a user to know if it is the new or old behaviour, in case they are
debugging memory problems, logs etc. How about:
"Delay creating or reusing a mempool for vhost ports until the vhost device has been
added."
I'm curious, does this change cause delayed error reporting
or we do not report error on add-port already?
Yeah, if it failed to get a mempool under both schemes, then the log
would appear at a later time now. That is part of what i was thinking
about when i mentioned debugging/logs.
I don't mind it be either way, it just maybe worth highlighting
for users.
Sure, I can add a short sentence to mention. e.g.
"Delay creating or reusing a mempool for vhost ports until the vhost
device has been added. A failure to create a mempool will now also be
logged when the vhost device is added."
Sounds ok?
Best regards, Ilya Maximets.
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