Re: vxWorks network problems

["Steven M. Hartman" <hartmansm@ornl.gov>]

Hi Dirk--

Dirk Zimoch wrote:

> I tried to tune the network buffers. But once I when I saw with 
> inetstatShow that send queues filled up, I increased their size from the 
> default 8k to 64k. This seems to be a bad decision, because now I don't 
> have enough mbufs any more. 

Were you tuning to address a particular problem you were experiencing?

In the scenario you described where the server had a full send queue 
and multiple clients had large receive queues, increasing the queue 
size is unlikely to help much. At best, it may just slightly delay 
the inevitable (or starve the server of resources first).

I would be more curious as to what was happening (client, server, 
network) that led to this peculiar situation. (One end of the 
connection briefly queuing up is not unusual for a busy system, but 
both ends seems strange.)

> It was user shift, so hopefully nobody had unplugged any cables. 

Could still be a flaky edge network switch. Or something unrelated.

> Probably ca_search UDP packages are related, but the time resolution of 
> our network diagnosis is not so good that I can see if the IOC crashes 
> because of search broadcasts or if the clients broadcast because the IOC 
> crashed.

I would guess the search broadcasts were the result of the IOC 
crash, not the cause.


--
Steven Hartman
hartmansm@ornl.gov