On 26-Jul-19 5:44 PM, Lipiec, Herakliusz wrote:
-----Original Message-----
From: Burakov, Anatoly
On 26-Jul-19 4:56 PM, Lipiec, Herakliusz wrote:
From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Burakov, Anatoly
On 26-Jul-19 4:01 PM, Stephen Hemminger wrote:
On Fri, 26 Jul 2019 10:53:58 +0100
"Burakov, Anatoly" <anatoly.bura...@intel.com> wrote:
NP to disallow it.
In fact, I think it would be easier for everyone just to drop
current DPDK MP model, and keep just standalone DPDK instances.
That's the dream, but i don't think it'll ever come to fruition, at
least not without a huge push from the community.
There are several net appliances that require primary/secondary model.
I think initially during DPDK development it was sold as a feature
to the Network vendors.
It might be possible to clamp down on what API's are supported by
secondary process. For example, disallowing any control operations
start/stop
etc.
We're getting slightly off topic here.
The original question was about whether we want to support a use case
where a secondary can initialize after primary process has died, and
if we don't, whether we want to 1) outright deny initialization, or
2) allow it, but document as unsupported and discourage it.
Allowing something that is unsupported sounds like asking for trouble.
We wouldn't be "allowing" it as much as we'd just be disclaiming any
responsibility for when things go wrong, *if* someone tries that. I suppose the
concern is that someone would try that /accidentally/, and possibly screw up
other secondary processes that may still be running.
The only use case i can think of that would require it is proc-info app.
Dumping stuff from a dead process can be useful for debugging, so perhaps
we
can agree to put a warning at EAL startup, saying that this is not supported,
but
still allow processes to initialize.
If this is supposed to be useful for debugging then maybe allow only when
some kind of flag is passed to eal?
This would also prevent from initializing the process incidentally.
We have too many EAL flags as it is! I suppose this could be done -
proc-info already hardcodes the "--proc-type" flag so that it only ever
runs as a secondary, we could add another one there. So, technically,
this is doable.
Well it’s a bad idea to allow this without any "yes I know what I'm doing"
I'm just not sure of the prospect of adding a yet another EAL flag to
serve a purpose of enabling one specific application to run. That said,
an "--i-know-what-i-am-doing" flag certainly sounds like a fun idea!
Well are there any other "unsupported" operations in dpdk ?
Maybe one "--i-(don’t)-know-what-i-am-doing" aka debug (devmode, dangerous or
whatever) flag
is a good option to enable/disable these kind of behaviours and cover them all,
this would definitely help preventing someone from doing this accidentally, or
unknowingly (for example from within a script).
To be completely clear, it's not like it's /dangerous/ to allow this
sort of init. At least not currently. Things like ports will be missing
from the process, but usually initialization is *attaching* to data, not
creating new one. So, allowing such unsupported scenario is, strictly
speaking, safe, at least for now.
I am not aware of any other "unsupported" operations that DPDK allows
you to do, so that would be a first. There are debug modes for various
libraries, but 1) they're compile time, 2) they're compile time for
performance reasons, meaning we can't bake them in and enable them with
a switch, and 3) they're not "unsupported", they're just not the default.
--
Thanks,
Anatoly
--
Thanks,
Anatoly
