[ovs-dev] [PATCH v4] ofproto-dpif-xlate: Implement RCU locking in ofproto-dpif-xlate.

Ryan Wilson wryan at vmware.com
Tue May 20 04:53:24 UTC 2014

So I did an experiment where I added 500 and 1000 ports and then deleted 500 and 1000 ports with and without this patch on both machines with 8 GB and 62 GB memory. Weirdly enough, adding / deleting ports with the RCU patch turned out to actually be faster than without. My only explanation here is taking the global xlate lock is expensive and / or 500 ports wasn't enough to induce memory pressure.

Here are the numbers for the 500 port case on a 8 GB memory machine:
WIth RCU patch:
Adding ports: real	1m15.850s
Deleting ports: real	1m21.830s

Without RCU patch:
Adding ports: real	1m28.357s
Deleting ports: real	1m33.277s

Ryan Wilson
Member of Technical Staff
wryan at vmware.com
3401 Hillview Avenue, Palo Alto, CA
650.427.1511 Office
916.588.7783 Mobile

On May 19, 2014, at 8:56 AM, Ben Pfaff <blp at nicira.com> wrote:

> On Fri, May 16, 2014 at 06:59:02AM -0700, Ryan Wilson wrote:
>> Before, a global read-write lock protected the ofproto-dpif / ofproto-dpif-xlate
>> interface. Handler and revalidator threads had to wait while configuration was
>> being changed. This patch implements RCU locking which allows handlers and
>> revalidators to operate while configuration is being updated.
>> Signed-off-by: Ryan Wilson <wryan at nicira.com>
>> Acked-by: Alex Wang <alexw at nicira.com>
> One side effect of this change that I am a bit concerned about is
> performance of configuration changes.  In particular, it looks like
> removing a port requires copying the entire configuration and that
> removing N ports requires copying the entire configuration N times.  Can
> you try a few experiments with configurations that have many ports,
> maybe 500 or 1000, and see how long it takes to remove several of them?
> _______________________________________________
> dev mailing list
> dev at openvswitch.org
> https://urldefense.proofpoint.com/v1/url?u=http://openvswitch.org/mailman/listinfo/dev&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=TfBS78Vw3dzttvXidhbffg%3D%3D%0A&m=Zs91K1%2FqNCTCBEK8%2FYn6ZxlWk8%2B9KnAmWsxIFslVMIM%3D%0A&s=d0a516ff3c7de6162c8224e60363e8159c1da0eabe5ede2e10d43b18858e965d

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openvswitch.org/pipermail/ovs-dev/attachments/20140519/eb88250d/attachment-0005.html>

More information about the dev mailing list