[ovs-discuss] a struct to keep flow scores

Ben Pfaff blp at ovn.org
Thu May 11 14:06:50 UTC 2017


OK.  I'm not certain why you need new high-level data structures for
this.  The code already propagates information from the datapath into
the OpenFlow flows and I think that you can just follow the existing
pattern to convey your new data.

On Thu, May 11, 2017 at 01:50:32PM +0000, Avi Cohen (A) wrote:
> Thanks Ben,
> We need to test another eviction criteria - not LRU, 
> but learn the flows other scores   such as flow effective time / flow usage , and to do eviction based on these scores
> Best Regards
> avi
> 
> > -----Original Message-----
> > From: Ben Pfaff [mailto:blp at ovn.org]
> > Sent: Thursday, 11 May, 2017 4:42 PM
> > To: Avi Cohen (A)
> > Cc: ovs-discuss at openvswitch.org
> > Subject: Re: [ovs-discuss] a struct to keep flow scores
> > 
> > OVS already has mechanisms for this kind of thing.  For datapath flows, OVS
> > already evicts flows based on these criteria.  For OpenFlow flows, OVS already
> > supports approximate-LRU eviction.  I'm not sure what you're going to
> > additionally get out of adding more to these mechanisms.  Do you have a high-
> > level goal?
> > 
> > On Thu, May 11, 2017 at 06:42:26AM +0000, Avi Cohen (A) wrote:
> > > Thanks  Ben,
> > > The general idea is to store flow info (pkt, bytes, last_time_used)
> > > which is updated every dumping phase and learn about flow behavior To
> > calculate  flow-usage and and flow-span scores in order to evict  flows based
> > this criteria.
> > >
> > > I thought of 2 implementation methods:
> > > 1st  impl. Methiod
> > > Store   the flow statistics  (pkt, bytes, last_time_used)  which is updated every
> > dumping phase in a  flow ring-buffer
> > > So we need to store info  of flows that are in openflow tables that
> > > were installed  at least one time  at dp-cache and currently are or aren't in
> > dp-cache The question is where to allocate this ring buffer ?
> > >
> > > 2nd impl. Method:
> > > Maintain a global sliding window contains all flows statistics, then
> > > at eviction phase - calculate the scores based on the sliding window
> > information The question is where to allocate this sliding window ?
> > > Best Regards
> > > avi
> > >
> > >
> > > > -----Original Message-----
> > > > From: Ben Pfaff [mailto:blp at ovn.org]
> > > > Sent: Thursday, 11 May, 2017 6:49 AM
> > > > To: Avi Cohen (A)
> > > > Cc: ovs-discuss at openvswitch.org
> > > > Subject: Re: [ovs-discuss] a struct to keep flow scores
> > > >
> > > > On Wed, May 10, 2017 at 07:12:27AM +0000, Avi Cohen (A) wrote:
> > > > > I need to keep some score information per flow - which exist in
> > > > > the open-flow
> > > > tables at user space , not necessarily in the data-path cache.
> > > > > These scores are learned during flow dumping phase - but should be
> > > > > saved
> > > > also when flow is evicted from data-path.
> > > > > The udpif_key struct is not suitable for this since it exist only
> > > > > when flow exist
> > > > in the data-path.
> > > > > What is the suitable structure to keep this info ?
> > > >
> > > > What kind of information is this?  How to deal with it depends on what it is.


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