[ofa-general] minimum sw components requirement for driver/opensm in a single unmanaged switch network

[Yicheng Jia]

Hi Hal,

Can opensm just run once? When the subnet is up, it can exit assume that 
no change will be made in the subnet.

Thanks!
Yicheng




"Hal Rosenstock" <hal.rosenstock at gmail.com> 
07/10/2008 09:15 PM

To
"Yicheng Jia" <YJia at tmriusa.com>
cc
"Jim Mott" <jim at mellanox.com>, general at lists.openfabrics.org
Subject
Re: [ofa-general] minimum sw components requirement for driver/opensm in a 
single unmanaged switch network






On Thu, Jul 10, 2008 at 7:39 PM, Yicheng Jia <YJia at tmriusa.com> wrote:
>
>> If you want to avoid all the SM stuff, and are willing to program the
>> switches directly (a few mads)
>
> Is it done by opensm?

Yes.

> What information should be set up in the switch by
> opensm?

Things like the PortInfos and LFT. See IBA spec vol 1 14.2.5

>> Then to figure out QP connections, you just use a function of 3
>> parameters:
>>  my_qp_num = fn_sqp(my_node, target_node, qp_num)
>>  target_qp_num = fn_tqp(my_node, target_node, qp_num)
>> Where qp_num is a small number between 0 and the maximum number of QPs 
you
>> need active between any 2 endpoints.
>
> Can the qp_num be manually assigned?
> Does it need opensm be involved?

SM has nothing to do with QP numbers.

>> If it works, you are done.  If not, reset, up, wait for him to connect 
and
>> send something to you.
>
> Is it reliable? I mean the QPs connection will keep alive during the QPs
> lifecycle?

For one thing, SM needs to try to keep ports at active.

-- Hal

> Best,
> Yicheng
>
>
>
> "Jim Mott" <jim at mellanox.com>
>
> 07/10/2008 04:17 PM
>
> To
> "Yicheng Jia" <YJia at tmriusa.com>, <general at lists.openfabrics.org>
> cc
> Subject
> RE: [ofa-general] minimum sw components requirement for driver/opensm in 
a
> single unmanaged switch network
>
>
>
>
> If you want to avoid all the SM stuff, and are willing to program the
> switches directly (a few mads), then I've used schemes like:
>
> Node LID=base + (switch port * constant) (base=0, constant = 1 works)
>
> Then to figure out QP connections, you just use a function of 3 
parameters:
>   my_qp_num = fn_sqp(my_node, target_node, qp_num)
>   target_qp_num = fn_tqp(my_node, target_node, qp_num)
> Where qp_num is a small number between 0 and the maximum number of QPs 
you
> need active between any 2 endpoints.
>
> With the above scheme, you know your node_id (switch port number), your 
lid,
> the lid of the target node,  and the QPs on both sides.  From there on, 
it
> is clear sailing.  You don't even need to send MADs; just transition the 
QP
> up and try and use it.  If it works, you are done.  If not, reset, up, 
wait
> for him to connect and send something to you.  A little timer to make 
sure
> everybody retries once in awhile and what can go wrong?
>
> Jim
> From: general-bounces at lists.openfabrics.org
> [mailto:general-bounces at lists.openfabrics.org] On Behalf Of Yicheng Jia
> Sent: Thursday, July 10, 2008 2:59 PM
> To: general at lists.openfabrics.org
> Subject: [ofa-general] minimum sw components requirement for 
driver/opensm
> in a single unmanaged switch network
>
>
> Hi Folks,
>
> I have a IB network which consists of only a single unmanaged switch, 
all
> end nodes connecting with the switch only need to do RDMA read/write
> operation with each other. My question is, what are the indispensable
> modules in driver's core and opensm that make the network up and run?
>
> I've been using only ib_mad module in driver's core with a managed 
switch
> before, and the network works fine. So I assume that only the ib_mad 
module
> in driver's core and SM in opensm are mandatory in my network. The LIDs 
are
> assigned by them. The SA and CM modules are not useful in my case. Am I
> right?
>
> I need to minimize driver and opensm to fit them in my network, the HCA
> driver is mthca.
>
> Best,
> Yicheng
> 
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