Open Stack

Hello John:

About the Trunk plugin and the RPC calls. This is a flaw in the design of
the Trunk service plugin. The RPC backend instantiated and the RPC calls
registered during the Neutron manager initialization. This is done before
the API and RPC workers are created. Because of this, the Trunk plugin RPC
calls are attended by the main thread only. That is something to be
improved for sure.

About the VXLAN ranges. It is recommended to limit the range that could be
used by Neutron. 4 seconds is still a lot of time for a table so simple
(two columns without any external reference). But for sure 3 minutes is not
practical. You need to investigate the poor performance of this engine with
this table. But as commented, in order to mitigate that poor performance,
you can probably reduce to 1K or 2K the number of VXLAN ranges.

I'll check the launchpad bug reported. Thanks!

Regards.

On Tue, Apr 4, 2023 at 6:09 PM Dmitriy Rabotyagov <noonedeadpunk at gmail.com>
wrote:

> Yes, totally, that would be great to sort out why using uWSGI make
> such difference in performance. I was just trying to provide you with
> a fix solution in the meantime, if its needed and affecting your
> production deployment.
>
> Also, if neutron_use_uwsgi is set to false, neutron-rpc-server should
> be stopped as this service is not used for scenario without uWSGI at
> all. Though I can imagine having a bug in OpenStack-Ansible that we
> leave neutron-rpc-server running when switching from uwsgi to
> eventlet, despite it not needed for that scenario.
>
> In addition to that, I'm not sure about the current state, but during
> Zed uWSGI known not to work at all with OVN driver, for instance. It
> could be fixed now though.
>
> вт, 4 апр. 2023 г. в 16:47, John Bartelme <bartelme at gmail.com>:
> >
> > Dmitriy wrote:
> > > Have you tried out of interest to set "neutron_use_uwsgi: false" in
> your user_variables.yml
> >
> >      Thank you for that suggestion.  I did think about changing that
> > option but reading up on some of the change logs it looked like
> > everything is trying to be migrated over to uWSGI.  When I set that
> > option things are indeed much better.  The update_subport_bindings RPC
> > call is still not being handled by the RPC worker threads but the
> > neutron-server parent thread is able to handle the calls and much more
> > quickly than the uWSGI threads were, i.e. in that 1-2 second
> > timeframe.   What are the ramifications of not using uWSGI?  Is this
> > an ok configuration for a production deployment?  Are there any
> > thoughts as to why the uWSGI threads are having such performance
> > issues?  Thanks so much for all of the help.
> >
> >      I’ll continue to write up a bug for RPC threads not handling
> > update_subport_bindings calls and for uWSGI handling them which may be
> > unexpected.
> >
> >      Thanks, john
> >
> > On 4/4/23, Lajos Katona <katonalala at gmail.com> wrote:
> > > Hi,
> > > Perfect, please do that.
> > >
> > > Lajos
> > >
> > > John Bartelme <bartelme at gmail.com> ezt írta (időpont: 2023. ápr. 4.,
> K,
> > > 15:12):
> > >
> > >> When you say trunk issue do you mean about the RPC calls going to
> > >> uWSGI threads or this general issue with long times.  For the long
> > >> times I'm not sure I have enough detail to write a bug but I could for
> > >> the RPC calls.
> > >>
> > >> Also I'm using LinuxBridge on the backend.
> > >>
> > >> Thanks, john
> > >>
> > >> On 4/4/23, Lajos Katona <katonalala at gmail.com> wrote:
> > >> > Hi,
> > >> > could you open a bug report on https://bugs.launchpad.net/neutron/
> for
> > >> the
> > >> > trunk issue with reproduction steps?
> > >> > It is also important which backend you use? OVS or something else?
> > >> >
> > >> > Thanks in advance
> > >> > Lajos Katona (lajoskatona)
> > >> >
> > >> > John Bartelme <bartelme at gmail.com> ezt írta (időpont: 2023. ápr.
> 4., K,
> > >> > 14:15):
> > >> >
> > >> >> Hello,
> > >> >>
> > >> >> I'm currently experiencing some pretty severe performance issues
> with
> > >> >> my
> > >> >> openstack-ansible deployed cluster(yoga) while deploying trunk
> ports
> > >> >> and
> > >> >> I'm looking for some help determining what might be the cause of
> this
> > >> >> poor
> > >> >> performance.
> > >> >>
> > >> >> In my simplest case I'm deploying 2 servers each with one trunk
> port
> > >> >> each.
> > >> >> The first trunk has 2 subports and the second 6 subports. Both
> servers
> > >> >> also
> > >> >> have 3 other regular ports. When deploying the first trunk port its
> > >> >> subports are often provisioned quickly and the second trunk port
> takes
> > >> >> anywhere from 30 seconds to 18 minutes. This happens even when I
> > >> >> isolate
> > >> >> neutron-server to a single physical machine with 44(88 threads) and
> > >> 256GB
> > >> >> ram. Further diagnosis has shown me some things i didn't quite
> > >> >> understand.
> > >> >> My deployment with OpenStack-ansible deploys neutron-server with 16
> > >> uWSGI
> > >> >> processes and neutron-rpc-server with 16 rpc workers. However the
> way
> > >> >> that
> > >> >> the trunk RPC server is implemented it is only run on the parent
> RPC
> > >> >> thread
> > >> >> and instead runs in all of the uWSGI processes as well. This means
> > >> >> that
> > >> >> most of my trunk RPC calls are being handled by the uWSGI instead
> of
> > >> >> the
> > >> >> RPC workers. When the parent RPC thread handles the trunk port
> > >> >> creation
> > >> >> calls I constantly see creation times of 1-1.5 seconds. I've
> isolated
> > >> >> it
> > >> >> so
> > >> >> that this thread does all of the trunk RPC calls and this works
> quite
> > >> >> well
> > >> >> but this doesn't seem ideal. What could be causing such poor
> > >> >> performance
> > >> >> in
> > >> >> the uWSGI side of the house? I'm having a really hard time getting
> a
> > >> good
> > >> >> feeling for what might be slowing it down so much. I'm wondering
> if it
> > >> >> could be green thread preemption but I really don't know. I've
> tried
> > >> >> setting 'enable-threads' false for uWSGI but I don't think that is
> > >> >> improving performance. Putting the profiled decorator on
> > >> >> update_subport_bindings shows different places taking longer every
> > >> >> time,
> > >> >> but in general a lot of time(tottime, i.e. not subfunction time)
> spent
> > >> in
> > >> >> webob/dec.py(__call__), paste/urlmap.py(__call__),
> > >> >> webob/request.py(call_application),webob/request.py(send). What
> else
> > >> >> can
> > >> >> I
> > >> >> do to try and look for why this is taking so long?
> > >> >>
> > >> >> As a side question it seems counterintuitive that the uWSGI handles
> > >> >> most
> > >> >> of
> > >> >> the trunk RPC calls and not the RPC workers?
> > >> >>
> > >> >> A couple other notes about my environment that could indicate my
> > >> >> challenges:
> > >> >>
> > >> >> I had to disable rabbitmq heartbeats for neutron as they kept not
> > >> getting
> > >> >> sent reliably and connections were terminated. I tried with
> > >> >> heartbeat_in_pthread both true and false but still had issues. It
> > >> >> looks
> > >> >> like nova also sometimes experiences this but not near as often.
> > >> >>
> > >> >> I was overzealous with my vxlan ranges in my first configuration
> and
> > >> gave
> > >> >> it a range of 10,000,000 not realizing that would create that many
> > >> >> rows
> > >> >> in
> > >> >> the database. Looking into that I saw that pymysql in my cluster
> takes
> > >> >> 3.5
> > >> >> minutes to retrieve those rows. mysql CLI only takes 4 seconds.
> > >> >> Perhaps
> > >> >> that is just the overhead of pymysql? I've greatly scaled down the
> > >> >> vxlan
> > >> >> range now.
> > >> >>
> > >> >> I'm provisioning the 2 servers with a heat template that contains
> > >> >> around
> > >> >> 200 custom resources. For 198 of the resources they are set to
> > >> >> conditionally not create any OpenStack native resources. Deploying
> > >> >> this
> > >> >> template of mostly no-op resources still takes about 3 minutes.
> > >> >>
> > >> >> Horizon works but almost every page load take a few seconds to
> load.
> > >> >> I'm
> > >> >> not sure if that is normal or not.
> > >> >>
> > >> >> Thanks for any help anyone can provide.
> > >> >>
> > >> >> john
> > >> >>
> > >> >>
> > >> >
> > >>
> > >
> >
>
>
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