OK.

My memory consumption comment is just quibbling.  I'd like to get in
the fix, then we can reduce the memory consumption if need be.

On Tue, Jun 03, 2014 at 03:14:01PM -0700, Alex Wang wrote:
> Yes, I have confirmed that this patch fix the bug.
> 
> 
> On Tue, Jun 3, 2014 at 3:11 PM, Ben Pfaff <b...@nicira.com> wrote:
> 
> > On Wed, Jun 04, 2014 at 09:51:16AM +1200, Joe Stringer wrote:
> > > On 4 June 2014 05:39, Alex Wang <al...@nicira.com> wrote:
> > >
> > > > I confirm this patch fix the bug, but have a high level concern,
> > > >
> > > >
> > > > Assume another learnt flow with hard_timeout=10 and was never hit after
> > > > install, now, if there is frequent change to the flow table and
> > > > need_revalidate
> > > > is constantly 'true', this learnt flow will never timeout...  since we
> > > > always
> > > > redo the flow_mod during revalidation,
> > > >
> > >
> > > (Correct me if I'm wrong, but this is how I see it:)
> > > For this particular case, we will not redo the flow_mod during
> > > revalidation. The "may_learn" flag is the same as before. Now, we will
> > > create the flow_mod and cache it, but only do the flow_mod if may_learn
> > is
> > > true.
> > >
> > > The "execute_learn" function is perhaps a bit misleading here: It only
> > > assembles the flow_mod, doesn't actually execute it.
> >
> > I think this is logically correct.  Have you confirmed that it fixes
> > the original bug?
> >
> > One concern I have is memory consumption.  struct ofputil_flow_mod is
> > 452 bytes (which we use and initialize), plus we allocate another 1024
> > bytes for actions.  I don't see an easy way to get rid of the former,
> > but I think that the actions would normally be pretty small.  I think
> > we'd probably be better off with an initial stub for the latter that
> > we then xmemdup() to save.  Alternatively, if you changed the starting
> > size of the actions ofpbuf to just, say, 64 bytes, I think that would
> > save a lot of memory in the common case.
> >
> > Assuming it fixes the bug,
> > Acked-by: Ben Pfaff <b...@nicira.com>
> >
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