Bryan> The ipath_sma.c file supports a lightweight userspace
Bryan> subnet management agent (SMA). This is used in deployments
Bryan> (such as HPC clusters) where a full Infiniband protocol
Bryan> stack is not needed.
I've never understood what forces you to maintain two separate SMAs.
Why can't you pick one of the two SMAs and use that unconditionally?
- R.
On Thu, 2006-03-09 at 15:20 -0800, Roland Dreier wrote:
> I've never understood what forces you to maintain two separate SMAs.
> Why can't you pick one of the two SMAs and use that unconditionally?
Three reasons.
* OpenSM wasn't usable when we wrote our SMA. We have customers
using ours now, so we have to support it.
* Our SMA does some setup for the layered ethernet emulation
driver.
* Our SMA works without an IB stack of any kind present.
<b
> Three reasons.
>
> * OpenSM wasn't usable when we wrote our SMA. We have customers
> using ours now, so we have to support it.
Huh? What does OpenSM working or not have to do with the SMA?
> * Our SMA does some setup for the layered ethernet emulation
> driver.
> * Our SMA works without an IB stack of any kind present.
That's fine. So then I guess the question is, why can't you use your
SMA all the time?
And does that mean that the verbs SMA doesn't support ethernet
emulation, so you can't use ethernet emulation and verbs at the same time?
- R.
On Thu, 2006-03-09 at 15:47 -0800, Roland Dreier wrote:
> That's fine. So then I guess the question is, why can't you use your
> SMA all the time?
We do. It coexists with OpenSM if OpenSM is present.
<b
Roland> That's fine. So then I guess the question is, why can't
Roland> you use your SMA all the time?
Bryan> We do. It coexists with OpenSM if OpenSM is present.
So can we kill the other SMA?
- R.
Quoting r. Bryan O'Sullivan <[email protected]>:
> Subject: Re: [PATCH 9 of 20] ipath - char devices for diagnostics and lightweight subnet management
>
> On Thu, 2006-03-09 at 15:20 -0800, Roland Dreier wrote:
>
> > I've never understood what forces you to maintain two separate SMAs.
> > Why can't you pick one of the two SMAs and use that unconditionally?
>
> Three reasons.
>
> * OpenSM wasn't usable when we wrote our SMA. We have customers
> using ours now, so we have to support it.
Presumably you mean the ib_mad SMA - OpenSM is not an SMA.
I don't understand this. You don't talk to an SMA directly -
its jobs is to receive and send management packets that the card
gets from a subnet manager. So what do customers care which SMA
implementation is used, as long as it formats the management packets
correctly?
If you want to extend the SMA in non-standard ways, you can
snoop and send management packets by loading ib_umad.
> * Our SMA does some setup for the layered ethernet emulation
> driver.
You are doing this from userspace, right? But you can already send/receive MADs
from userspace by loading ib_umad. What is there that is not sufficient for
your purposes?
By the way, this might also be a clean way for you to get at the port info
node info and port counters atomically like you wanted to in another thread:
post a management packet to the local device, get a packet back.
No need for extra sysfs files.
> * Our SMA works without an IB stack of any kind present.
The stack is pretty slim, AFAIK it mostly consists of an SMA implementation.
So where's the benefit in avoiding it? Just link against ib_mad, it will
get loaded atomatically.
--
Michael S. Tsirkin
Staff Engineer, Mellanox Technologies
On Fri, 2006-03-10 at 17:54 +0200, Michael S. Tsirkin wrote:
> > * OpenSM wasn't usable when we wrote our SMA. We have customers
> > using ours now, so we have to support it.
>
> Presumably you mean the ib_mad SMA - OpenSM is not an SMA.
Yes, I already mentioned that I got my terms swapped in another message.
> So what do customers care which SMA
> implementation is used, as long as it formats the management packets
> correctly?
Many, perhaps most right now, of our customers don't have a full IB
stack loaded. That's why we have this small userspace SMA.
<b