[spp] [Bug 443] spp primary takes up the complete hugepages

[bugzilla at dpdk.org]

https://bugs.dpdk.org/show_bug.cgi?id=443

--- Comment #14 from Vipin Varghese (vipin.varghese at intel.com) ---
Hello Masahiro,

thank you for taking time and trying to understand the details. Following is my
answers shared below

1, memory management of DPDK
[Answer] for all final decision and right setup please reach out to DPDK memory
manamangent maintainer. I can only suggest what I know.

Q1. If user specify enough memory with '--socket-mem'(e.g. 5Gbytes), then no
need to think about '--socket-limit'.
[Answer] this is not the right understanding, because `socket-limit` is the
upper (maximum) limit. This is been explained in comment-1.

Q2. '--socket-limit' specifies upper limit of memory usage regardless of
'--socket-mem' value. Then what is the risk(e.g. performance) when user specify
'--socket-limit' without '--socket-mem'
[Answer] yes this is good argument, but only valid if there are not more than 2
primary application. In use cases (SPP is being used mostly) which has VM and
dockers. So if one intents to ensure SPP primary requires minimum 512MB use
`--socket-mem` and to ensure that dynamic allocations in SPP does not cross
over 2048MB use `--socket-limit`

4. But it depends on 'characteristic of DPDK application',right? 
[Answer]Yes, I have explained the use case scenario. But for SPP this is not
the cazse.

At least, SPP does NOT need additional memory in runtime (rather primary
process allocate memory only during initialization).
[Answer] I think this is incorrect understand, If SPP is only standalone
application there are no Docker, VM or Pod which will not dynamically grow or
resize then you are safe not using the same.

In addition, adding many parameters may lead to 'confusion' or 'mistype'
and needs much workload to update documents.
[Answer] I find this is as very inconsistent argument because 'if the intention
is not to confuse users with argument, SPP should be hiding or abstract all EAL
arguments from end user which it is failing to do'

Your advice is highly appreciated. What do you think?
[Answer] I think you should take this up with `Hideyuki Yamashita` (maintainer)
on the direction of discussion and fixes. 


Note: Would not you agree, for the confirmed issue if the direction of the fix
is not clear 

1. there should have been meeting invitee or brain storming invites for the
same. 

2. If the goal is not to confuse end user with option, the SPP should be
abstracting or templating EAL arg with zero maintenance.


Hope all these will be fixed soon.

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