Re: [ovs-dev] [PATCH net-next 0/9] optimize openvswitch flow looking up

[William Tu <u9012063@gmail.com>]

Hi Tonghao,

Thanks for the patch.

> On 29 Sep 2019, at 19:09, xiangxia.m.yue@gmail.com wrote:
>
> > From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> >
> > This series patch optimize openvswitch.
> >
> > Patch 1, 2, 4: Port Pravin B Shelar patches to
> > linux upstream with little changes.
> >

I thought the idea of adding another cache before the flow mask
was rejected before, due to all the potential issue of caches, ex:
cache is exploitable, and performance still suffers when your cache
is full. See David's slides below:
[1] http://vger.kernel.org/~davem/columbia2012.pdf

Do you have a rough number about how many flows this flow mask
cache can handle?

> > Patch 5, 6, 7: Optimize the flow looking up and
> > simplify the flow hash.

I think this is great.
I wonder what's the performance improvement when flow mask
cache is full?

Thanks
William

> >
> > Patch 8: is a bugfix.
> >
> > The performance test is on Intel Xeon E5-2630 v4.
> > The test topology is show as below:
> >
> > +-----------------------------------+
> > |   +---------------------------+   |
> > |   | eth0   ovs-switch    eth1 |   | Host0
> > |   +---------------------------+   |
> > +-----------------------------------+
> >       ^                       |
> >       |                       |
> >       |                       |
> >       |                       |
> >       |                       v
> > +-----+----+             +----+-----+
> > | netperf  | Host1       | netserver| Host2
> > +----------+             +----------+
> >
> > We use netperf send the 64B frame, and insert 255+ flow-mask:
> > $ ovs-dpctl add-flow ovs-switch
> > "in_port(1),eth(dst=00:01:00:00:00:00/ff:ff:ff:ff:ff:01),eth_type(0x0800),ipv4(frag=no)"
> > 2
> > ...
> > $ ovs-dpctl add-flow ovs-switch
> > "in_port(1),eth(dst=00:ff:00:00:00:00/ff:ff:ff:ff:ff:ff),eth_type(0x0800),ipv4(frag=no)"
> > 2
> > $ netperf -t UDP_STREAM -H 2.2.2.200 -l 40 -- -m 18
> >
> > * Without series patch, throughput 8.28Mbps
> > * With series patch, throughput 46.05Mbps
> >
> > Tonghao Zhang (9):
> >   net: openvswitch: add flow-mask cache for performance
> >   net: openvswitch: convert mask list in mask array
> >   net: openvswitch: shrink the mask array if necessary
> >   net: openvswitch: optimize flow mask cache hash collision
> >   net: openvswitch: optimize flow-mask looking up
> >   net: openvswitch: simplify the flow_hash
> >   net: openvswitch: add likely in flow_lookup
> >   net: openvswitch: fix possible memleak on destroy flow table
> >   net: openvswitch: simplify the ovs_dp_cmd_new
> >
> >  net/openvswitch/datapath.c   |  63 +++++----
> >  net/openvswitch/flow.h       |   1 -
> >  net/openvswitch/flow_table.c | 318
> > +++++++++++++++++++++++++++++++++++++------
> >  net/openvswitch/flow_table.h |  19 ++-
> >  4 files changed, 330 insertions(+), 71 deletions(-)
> >
> > --
> > 1.8.3.1
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