[ovs-dev] [PATCH v1] doc: Remove experimental tag for SMC cache.

Ian Stokes ian.stokes at intel.com
Wed Jul 3 16:58:18 UTC 2019

On 6/27/2019 12:44 PM, Yipeng Wang wrote:
> SMC cache was introduced in 2.10 with experimental tag.
> SMC cache is a layer of software cache located after EMC
> cache. The purpose is to improve the performance of use
> cases that many flows missing the EMC cache.
> One can enable SMC cache using smc-enable=true option.

Thanks for this Yipeng.

I'd raised the topic of removing the experimental tag at the community 
call previously.

I guess two aspects were called out that form part of the litmus test 
for when the tag should be removed.

1. Is the feature in use in common/commercial use?
2. Are there any to-dos or known bugs to be resolved?

WRT point 1, I do believe it has been used/tested in commercial 
deployments and has been benchmarked against realistic deployments with 
positive results over EMC (except when there is only a small number of 
flows). I believe this was even presented by Red Hat at the OVS 
conference last year, so this is encouraging.

WRT to known bugs I'm not aware of any outstanding. There have been a 
handful of patches upstreamed since 2.10 to address some minor issues.

I think it's ok to remove this tag for the 2.12 release.

Would be interested to hear others thoughts?


> Signed-off-by: Yipeng Wang <yipeng1.wang at intel.com>
> ---
>   Documentation/topics/dpdk/bridge.rst | 4 ++--
>   NEWS                                 | 1 +
>   2 files changed, 3 insertions(+), 2 deletions(-)
> diff --git a/Documentation/topics/dpdk/bridge.rst b/Documentation/topics/dpdk/bridge.rst
> index a3ed926..71e1af6 100644
> --- a/Documentation/topics/dpdk/bridge.rst
> +++ b/Documentation/topics/dpdk/bridge.rst
> @@ -117,7 +117,7 @@ It is also possible to enable/disable EMC on per-port basis using::
>   For more information on the EMC refer to :doc:`/intro/install/dpdk` .
> -SMC cache (experimental)
> +SMC cache
>   -------------------------
>   SMC cache or signature match cache is a new cache level after EMC cache.
> @@ -125,7 +125,7 @@ The difference between SMC and EMC is SMC only stores a signature of a flow
>   thus it is much more memory efficient. With same memory space, EMC can store 8k
>   flows while SMC can store 1M flows. When traffic flow count is much larger than
>   EMC size, it is generally beneficial to turn off EMC and turn on SMC. It is
> -currently turned off by default and an experimental feature.
> +currently turned off by default.
>   To turn on SMC::
> diff --git a/NEWS b/NEWS
> index 2f8171f..bf99295 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -29,6 +29,7 @@ Post-v2.11.0
>        * New action "check_pkt_len".
>        * Port configuration with "other-config:priority-tags" now has a mode
>          that retains the 802.1Q header even if VLAN and priority are both zero.
> +     * Removed experimental tag for SMC cache.
>      - OVSDB:
>        * OVSDB clients can now resynchronize with clustered servers much more
>          quickly after a brief disconnection, saving bandwidth and CPU time.

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