[ewg] OpenSM 1.5.4 Boot Problem

Wed Dec 14 10:41:05 PST 2011

Hal,

Sorry for the multiple emails, but I was thinking how it may be a "freeze 
/stall" rather than a time out.  One reason is that it doesn't send an 
error message, is as if the log completely dies. However, in file 
osm_vendor_ibumad.c under function umad_receiver there is an infinite loop 
"for(;;)" which seems to die when I get to that previously discussed 
vl15_poller. I checked to see if it breaks out of the loop but it doesn't 
seem to. I'm not sure if this may be an additional hint.
Thank you

Hector Abrach

From:
Hector Abrach <HAbrach at TMRIUSA.COM>
To:
Hal Rosenstock <hal at dev.mellanox.co.il>
Cc:
ewg at lists.openfabrics.org
Date:
12/14/2011 11:15 AM
Subject:
Re: [ewg] OpenSM 1.5.4 Boot Problem
Sent by:
ewg-bounces at lists.openfabrics.org

Hal, 

Thank you very much for the support, I am the same person from the gmail 
account so I will respond through here. 

Attached is a picture of the switch serial number: 

I am indeed using OFED 1.5.4-rc3. My experiment consists of a 7 server 
system which I reboot via a script over and over again. Technically 
speaking the switch is not being powered off or physically rebooted. My 
server system is what is being rebooted. I am running OpenSM on one of the 
7 servers. This means I'm constantly shutting down and rebooting OpenSM. I 
am running OpenSM on QNX but we have not had this problem until we decided 
to upgrade to this switch. 

The problem is that every 1 out of 15 of this remote reboots OpenSM stalls 
or times out because stats->qp0_mads_outstanding did not reach zero. 
Please excuse my ignorance as I'm relatively new at this but how do I 
verify if it is a timeout problem vs a stall? 

You also mentioned that you'd like to see the Verbose output of openSM; 
however, when I run in Verbose mode I don't see the problem. It appears as 
if the verbose output stalls enough time to give the switch time to do 
what ever it needs to do and hence not have the problem occur. But this is 
the last I see when the problem occurs: 

------------------------------------------------- 
OpenSM 3.3.12 
Command Line Arguments: 
 Log file max size is 5 MBytes 
 Log File: /tmp/opensm.log 
------------------------------------------------- 
OpenSM 3.3.12 

Entering DISCOVERING state 

Using default GUID 0x2c9020023277d 

The problem occurs in function osm_vl15intf.c -> vl15_poller in the else 
statement. 

if (p_madw != (osm_madw_t *) cl_qlist_end(p_fifo)) { 
        OSM_LOG(p_vl->p_log, OSM_LOG_DEBUG, 
        "Servicing p_madw = %p\n", p_madw); 
        if (osm_log_is_active(p_vl->p_log, OSM_LOG_FRAMES)) 
        osm_dump_dr_smp(p_vl->p_log, 
        osm_madw_get_smp_ptr(p_madw), 
        OSM_LOG_FRAMES); 

        vl15_send_mad(p_vl, p_madw); 
} else 
        /* 
           The VL15 FIFO is empty, so we have nothing left to do. 
         */ 
        status = cl_event_wait_on(&p_vl->signal, 
                  EVENT_NO_TIMEOUT, TRUE); 

It won't move forward from the cl_event_wait_on in this line of code. 
However, there are other locations such as wait_for_pending_transactions 
in the do_sweep function that won't move forward from. But I believe this 
to be a side effect of the problem I'm mentioning. 

When you mention what is my timeout, I'm guessing you refer to 
max_smps_timeout which is used in the second while loop within 
vl15_poller? For this setting I am using the default which is defined in 
osm_subnet.c as: 

p_opt->transaction_timeout = OSM_DEFAULT_TRANS_TIMEOUT_MILLISEC; 
    p_opt->transaction_retries = OSM_DEFAULT_RETRY_COUNT; 
    p_opt->max_smps_timeout = 1000 * p_opt->transaction_timeout 
*p_opt->transaction_retries; 

Would you explain to me what are the advantages or disadvantages of 
OSM_DEFAULT_SMP_MAX_ON_WIRE? Does this parameter change my bandwidth 
performance at all? 

I noticed that when using the default setting of 4 I get into the else of 
the above if statement when there are 4 qp0_mads_outstanding. I noticed 
that if I change OSM_DEFAULT_SMP_MAX_ON_WIRE to 1 I don't get the failure 
I'm mentioning at all. Partly (I think) because I don't enter the else in 
the if statement until there is 1 qp0_mads_outstanding. 

I hope this explains the problem well enough and it may be a time out 
problem but I'd like to understand why the problem is occurring. 
Thank you very much, 

Hector Abrach 

From: 
Hal Rosenstock <hal at dev.mellanox.co.il> 
To: 
Hector Abrach <HAbrach at TMRIUSA.COM> 
Cc: 
ewg at lists.openfabrics.org 
Date: 
12/14/2011 08:03 AM 
Subject: 
Re: [ewg] OpenSM 1.5.4 Boot Problem

Hi,

On 12/13/2011 2:35 PM, Hector Abrach wrote:
> Hello,
> 
> I have a boot problem with OpenSM

Are you saying the switch is booted rather than OpenSM ?

What is the OpenSM running on and in what environment ?

> the problem occurs seldomly and
> started to ocur when we started using a new Mellanox MT1118X03342 
switch.
> The problem occurs during the discovery phase within 
state_mgr_sweep_hop_1.
> 
> However, I discovered that the actual location is because the
> qp0_mads_outsanding stalls at 1 occasionally.

Is it stuck or after timeout/retry does this get updated properly ?

> Within file osm_vl15intf.c in function vl15_poller it checks at the
> rfifo and if the qlist still has items it applies function vl15_send_mad
> which later on triggers the signal.
> With the current default setting of 4 for OSM_DEFAULT_SMP_MAX_ON_WIRE I
> noticed that cl_qlist_end reaches zero before
> stats->qp0_mads_outstanding does. This causes a stall in
> cl_event_wait_on. The rfifo always reaches 0 when there are 4
> qp0_mads_outstanding however when it fails it always fails when there is
> 1 qp0_mad_outstanding.

Is some (request) SMP that OpenSM sent timing out (not being responded to) 
?

> Have you seen this failure? By the way, I see this failure once every 15
> reboots approximately.
> 
> I discovered that changing OSM_DEFAULT_SMP_MAX_ON_WIRE to 1 fixes the
> problem.

What do you mean exactly by fixes the problem ? I'm not sure I
understand what the problem is yet.

-- Hal

> My guess is that there is a race condition when the switch sends 4 SMPs
> in parallel. Also, this failure only appears to occur at reboot. Another
> solution which is not acceptable is when I add a delay in the process
> the failure goes away. This as if the switch needed more time to do
> something.
> 
> I would really appreciate your help and insight.
> Thank you
> 
> Hector Abrach
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud 
service.
> For more information please visit http://www.symanteccloud.com
> ______________________________________________________________________
> 
> 
> _______________________________________________
> ewg mailing list
> ewg at lists.openfabrics.org
> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ewg

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________[attachment 
"2011-12-13_10-18-25_182.jpg" deleted by Hector Abrach/Software/TMRU] 
_______________________________________________
ewg mailing list
ewg at lists.openfabrics.org
http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ewg

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openfabrics.org/pipermail/ewg/attachments/20111214/52918541/attachment.html>