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<== Date ==> <== Thread ==>

Subject: Re: vxWorks network problems
From: "Steven M. Hartman" <hartmansm@ornl.gov>
To: Dirk Zimoch <dirk.zimoch@psi.ch>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Tue, 24 May 2011 09:19:41 -0400
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

References:
vxWorks network problems Dirk Zimoch
Re: vxWorks network problems Steven M. Hartman
Re: vxWorks network problems Dirk Zimoch

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