> On 01/06/2022 14:30, David Marchand wrote:
> > On Wed, May 25, 2022 at 1:11 PM Kevin Traynor
> <[email protected]> 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 <[email protected]>
> >> Reviewed-by: David Marchand <[email protected]>
> >
> > 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."

Hi Kevin, this looks good to me and tested ok.

If you'd like I can add the item to NEWS on commit?

Regards
Ian
> 
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