RT subsystem

From: Jonathan Williams (jonathw@shubertorg.com)
Date: Fri Nov 15 2002 - 14:58:33 EST

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I've got a question about some of the attributes under the RT subsystem under
Tru64 5.1 (patch 3) and 5.1a. (no patches)

In the Machine Notes for Informix Dynamix Server 9.30.FC1X6, it mentions that if
you run out of KAIO (Kernel Asynchronous I/O) resources, check the following
kernel configuration attributes:
aio_max_percent
aio_max_retry
aio_retry_scale
aio_task_max_num
sigqueue_max_num

So of course we ran out of these "KAIO" resources today...actually it didn't
seem to do anything obviously negative to our server, other than putting the
following in the Informix Log for a period of about 4 minutes:

13:19:22 KAIO: out of OS resources, errno = 35, pid = 65104

Now I went through every document I have, and can't find any information on what
to change these values to--or what these values even mean. So what book would I
look at to find out about these attributes? and are there any recommended
settings for Informix users? The machine in question is an Alpha ES40, running
Tru64 5.1 (patch 3), 4 GB RAM, I'm not sure what else is important.

Anyway, MY setting for those attributes is as follows:

rt:
         aio-max-percent=1
         aio-max-retry=0
         aio-retry-scale=4
         aio-task-max-num=102
         sigqueue-max-num=64

A few weeks ago when I asked about system tuning, someone mentioned the RT
subsystem, and that their values were:

rt:
         aio-max-percent=5
         aio-max-retry=20
         aio-retry-scale=5
         aio-task-max-num=2048
         sigqueue-max-num=128

I sent them an email asking how they came up with those numbers, but I never got
a reply back.

So, any help (specifically either pointing me to the correct documentation, or
suggestions with explanations on the actual attributes) would be greatly
appreciated. TIA

Jonathan Williams
Unix Systems Administrator
The Shubert Organization, Inc.

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