Hi, just wanted to send a follow-up and a test result.
I got everything up and running (yay!). So I set up a server and ran a
sandbox test using ovn with traditional C-based ovn-northd and then ran
the same test using ovn with DDlog-based ovn-northd.
The test script can be found here:
https://gist.github.com/putnopvut/3df7156b6d44b81d75a598262c5e959b
The test sets up a network with 159 logical switches all connected to a
single logical router. Each logical switch has 92 logical switch ports.
For every 2 logical switch ports we add, we create a new port group, and
ACLs are created for each port group. The important part of this test is
that the final call to ovn-nbctl in each iteration of the loop uses
--wait=sb. In other words, each new logical switch port we add has to
wait for ovn-northd to process it completely before we can start adding
the next logical switch port.
With traditional C-based ovn-northd:
[root@wsfd-netdev67 tutorial]# time ./scale-daemon-new-pg.sh
real 128m59.280s
user 1m27.601s
sys 2m0.986s
With DDlog-based ovn-northd:
[root@wsfd-netdev67 tutorial]# time ./scale-daemon-new-pg.sh
real 33m40.586s
user 1m26.976s
sys 1m59.784s
As you can see, the test takes about a quarter of the time to complete
when running with DDlog. So far, it seems like a good improvement.
As a point of reference, if I remove the --wait=sb from the test, then
the result is:
[root@wsfd-netdev67 tutorial]# time ./scale-daemon-new-pg.sh
real 3m59.696s
user 1m18.937s
sys 1m44.669s
This test was run with DDlog-based ovn-northd, but the result is nearly
identical with C-based ovn-northd since the test no longer is bound by
ovn-northd's performance.
I'm a bit surprised that with DDlog, adding --wait=sb to each iteration
causes such a large difference in the overall test time (~4 minutes up
to ~34 minutes).
My next step is going to be to plot the time of each individual
iteration during the test. I'll share those results when I have them
ready. I don't want to speculate on anything until I have that data to
share.
Thanks,
Mark Michelson
On 7/15/19 12:34 PM, Leonid Ryzhyk wrote:
Hi Mark,
Thanks for the feedback. We will add the `--version` flag.
Yes, `stack install` merely copies the two DDlog executable to
`~/.local/bin/` (or a custom path specified using `--local-bin-path
<custom_path>`).
Also, just want to mention that we maintain up-to-date binary releases
of DDlog at `https://github.com/vmware/differential-datalog/releases`,
so most users should not need to install the Haskell tool stack and
compile DDlog. When using binary releases, all you have to do is add the
`ddlog/bin` directory to `$PATH`.
Leonid
On Mon, Jul 15, 2019 at 6:30 AM Mark Michelson <[email protected]
<mailto:[email protected]>> wrote:
I did install DDlog originally back in early December last year. So
there are probably remnants of that still present. However, I did
perform a `stack install` using an updated pull of master on Friday. So
I guess the `stack install` didn't get rid of the old installation?
Also, there's no `ddlog --version` or anything similar to see what
version of DDlog is installed. That could be a nice feature to have in
the near future.
On 7/12/19 12:40 PM, Leonid Ryzhyk wrote:
> Thanks for trying it out! Sounds like you have a very old
version of
> ddlog. If you install from source, please make sure that you run
`stack
> install` and that there is no other version off ddlog in your
path other
> than the one created by `stack install`.
>
> Leonid
>
> On Fri, Jul 12, 2019, 9:05 AM Mark Michelson <[email protected]
<mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> On 7/12/19 3:29 AM, Leonid Ryzhyk wrote:
> > Dear OVN developers,
> >
> > This is a brief update on the state of the DDlog port of
ovn-northd.
> >
> > We completed the initial implementation of ovn-northd in DDlog
> few months
> > ago. Justin kindly
> > helped to integrate it with OVN, so that it can be used as
a drop-in
> > replacement for the C
> > version (and passes all the tests in the OVN test suite).
The DDlog
> > implementation does
> > not have any of the new features/improvements added in
April 2019
> or later.
> >
> > ## Repository
> >
> > The code is in the `ddlog-dev` branch of the `ovn-org/ovn`
> repository:
> > https://github.com/ovn-org/ovn/tree/ddlog-dev
>
> Hi Leonid,
>
> I ran into an issue when attempting to build ovn-northd. I
successfully
> installed DDLog, but then I encountered this issue when
building OVN:
>
> ddlog -i ovn/northd/ovn_northd.dl -L
> /home/putnopvut/differential-datalog/lib
> ddlog: Failed to parse input file: "ovn/northd/ovn_northd.dl"
(line 94,
> column 5):
> unexpected "&"
> expecting "not", variable name, relation name, "var",
expression or "."
>
> The line in question looks like this:
>
> &SwitchPort(.lsp = lsp, .sw = &sw),
>
> Any idea what's gone wrong here?
>
> Thanks,
>
> Mark Michelson
>
>
>
> >
> > ## Documentation
> >
> > Building and using ovn-northd-ddlog:
> >
>
https://github.com/ovn-org/ovn/blob/ddlog-dev/ovn/northd/docs/design.md
> >
> > Debugging ovn-northd-ddlog:
> >
>
https://github.com/ovn-org/ovn/blob/ddlog-dev/ovn/northd/docs/debugging.md
> >
> > ## Preliminary performance results
> >
> > Han Zhou kindly tested ovn-northd-ddlog with his OVN scale
test
> and even
> > found a nasty
> > performance bug in the process (thanks, Han!). He reports
that DDlog
> > speeds up the test
> > by almost a factor of 10:
> >
> > - ddlog version: 7:39min
> > - C version: 67:47min
> >
> > This is great, and in fact profiling shows that there is still
> plenty of
> > space for
> > improvement. He also reports a 10+ times increase in memory
> footprint:
> >
> > - ddlog version: 1944696KB
> > - C version: 147984KB
> >
> > Again, we are working on a number of optimizations, which
should
> reduce
> > this overhead; although it will never be as low as C,
since DDlog
> > fundamentally
> > needs to cache more state to enable fast incremental
computation.
> >
> > Han also used DDlog's record&replay feature to capture all
northd
> > transactions
> > performed by the scale test in a format that can be replayed
> against the
> > standalone DDlog executable without having to reproduce Han's
> OpenStack
> > setup.
> > The replay file is here: http://ryzhyk.net/replay.tgz
> >
> > Instructions for replaying this script:
> >
>
https://github.com/ovn-org/ovn/blob/ddlog-dev/ovn/northd/docs/debugging.md#record-and-replay-ddlog-execution
> > The script will run for a few
> > minutes and finally print some profiling information,
including the
> > breakdown of
> > DDlog's CPU and memory usage.
> >
> > ## Next steps
> >
> > We seek help from the OVN community in maintaining
> ovn-northd-ddlog. The
> > first
> > step is to start porting new OVN features introduced in
the last
> few months
> > to
> > DDlog.
> >
> > Leonid
>
> Hi Leonid,
>
> I attempted
>
> > _______________________________________________
> > dev mailing list
> > [email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> >
>
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