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

Ben Pfaff blp at nicira.com
Mon May 19 15:56:19 UTC 2014

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?

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