[ovs-dev] [patch_v10] ovn: Add datapaths of interest filtering.

Darrell Ball dball at vmware.com
Wed Dec 7 04:03:15 UTC 2016



On 12/6/16, 7:08 PM, "ovs-dev-bounces at openvswitch.org on behalf of Russell Bryant" <ovs-dev-bounces at openvswitch.org on behalf of russell at ovn.org> wrote:

    On Tue, Dec 6, 2016 at 3:35 PM, Ben Pfaff <blp at ovn.org> wrote:
    
    > On Tue, Dec 06, 2016 at 02:45:19PM -0500, Russell Bryant wrote:
    > > On Mon, Dec 5, 2016 at 2:22 AM, Ben Pfaff <blp at ovn.org> wrote:
    > >
    > > > On Sun, Dec 04, 2016 at 04:13:44PM -0800, Darrell Ball wrote:
    > > > > This patch adds datapaths of interest support where only datapaths of
    > > > > local interest are monitored by the ovn-controller ovsdb client.  The
    > > > > idea is to do a flood fill in ovn-controller of datapath associations
    > > > > calculated by northd. A new column is added to the SB database
    > > > > datapath_binding table - related_datapaths to facilitate this so all
    > > > > datapaths associations are known quickly in ovn-controller.  This
    > > > > allows monitoring to adapt quickly with a single new monitor setting
    > > > > for all datapaths of interest locally.
    > > >
    > > > Hi Darrell, the series I just sent out has some relevance here.  It
    > > > makes ovn-controller only implement the datapaths and ports flows that
    > > > are relevant to a given hypervisor, even though it does not affect what
    > > > part of the database is replicated.  The particularly relevant patch is
    > > > this:
    > > >         https://urldefense.proofpoint.com/v2/url?u=https-3A__patchwork.ozlabs.org_patch_702608_&d=DgICAg&c=uilaK90D4TOVoH58JNXRgQ&r=BVhFA09CGX7JQ5Ih-uZnsw&m=qWAPHpdqV7RcWokRLBU_mikSMVTnTefdf_BqOa0D9xE&s=iRVMW7EreZ7g-20aDnp497XNOeX0UbLTtBG0HHDPYXQ&e= 
    > > >
    > > > I suggest having a look at the series.
    > > >
    > >
    > > I'm in the middle of doing some control plane performance testing using
    > > OpenStack and OVN.  I may have time to do another run with some
    > additional
    > > patches applied to see how they affect performance.  Ideally I'd be able
    > to
    > > do that this week, though.
    > >
    > > If I'm able to fit this in, what do you guys suggest if I've only got one
    > > shot?  This patch or Ben's series?
    >
    > This series is aimed more at technical debt and code clarity than at
    > performance.  It might help with performance, but that's not the main
    > goal.
    >
    > Darrell/Liran's series is motivated by performance.  If it doesn't help
    > performance, then probably it shouldn't be applied because it makes the
    > code harder to understand.  (Disclaimer: I haven't read the recent
    > versions.)
    >
    
    I just deployed this change in my environment and was not able to observe a
    noticeable difference in CPU consumption of ovn-controller.  (ovn-northd
    was updated, as well.)
    
    The scenario was creating 500 VMs through OpenStack at a concurrency of 64
    (up to 64 VMs at a time).  Each VM also received its own network.  The 500
    VMs were distributed among 9 hypervisors.  Once all 500 VMs were up, they
    were all deleted.

Your results seem to be quite different than Liran’s. What is the difference ?

How many:
1) logical routers
2) gateway routers
 do you have ?

Sounds like this test boots up 500 VMs, checking for all to be created and then deletes them
and then ends ? 

    The CPU consumption looked roughly the same both before and after the patch
    and time to complete the test scenario was also similar.
    
    ovn-controller hits 100% CPU about 30% of the way into creating VMs and
    stays there until we finish creating them and start deleting them instead.
    
    -- 
    Russell Bryant
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