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

Ilya Maximets i.maximets at samsung.com
Thu Jul 4 10:12:35 UTC 2019

On 03.07.2019 19:58, Ian Stokes wrote:
> 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?

Hi, Ian and Yipeng.

SMC seems stable enough now. Since fixing one major bug last year I
didn't noticed about new issues, however I didn't try to use it in
long-living setups.
This change doesn't enable SMC by default, so it's totally OK for
me to remove the experimental tag. This way we'll, probably, have
more users of this feature and subsequently more testing that will
allow us to enable it by default for a next releases.

So, idea is good. One comment inline for the patch itself. And
rebase is needed also.

Best regards, Ilya Maximets.

> Regards
> Ian
>> 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
>>   -------------------------

Above line should be shortened according to the new section name
to be rST compliant, otherwise it will trigger a warning/error
while docs generation.

>>     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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