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My kernel usage is running up to 54%. What could that mean? What could be eating resources on this AIX machine?

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Downvoters should provide constructive criticism instead. – Thorbjørn Ravn Andersen Jun 17 '11 at 14:42
Since IO is the major kernel function that sits outside userland, you might want to add some IO related usage to narrow down what is happening. If there's work to do, that's why the kernel is busy. I have had heavily loaded systems run at 80% kernel for weeks at a time and gotten great amounts of work done on a system that was well tuned. – bmike Jul 7 '11 at 2:01
up vote 2 down vote accepted

This most likely mean that the kernel spends a lot of time talking to devices, probably your disk and a reasonable cause could be swapping.

You need to use an AIX System administration book to find the exact tools to identify exactly what is going on. If AIX has "sar" this is a very powerful tool, but otherwise "iostat" and "vmstat" will give you a good idea of what goes wrong, and you then have to figure out why this happens.

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A single snapshot of CPU load isn't very useful, additionally we'd need to understand the configuration of the machine (is it an micro-partition, what's the entitled capacity, how many virtual CPU's, etc.)

Ultimately, you need to investigate the issue using something like nmon (topas_nmon if your version of AIX has it built in).

If the machine is truly then you should also patch to a much, much more recent version of AIX before you worry too much about a single performance issue.

So in summary - there's no where near enough information to reasonably answer your query.

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+1 for your mention of the right tools and the need to patch first, but much of this answer should probable be moved to comments on the question. We try to keep answers paired down to just answers and keep the meta chatter in comments. – Caleb Jun 17 '11 at 16:02
I don't see an 'add comment' on anything but your comment - I'll read up and see how I could have left one on the original question (which I would have, if I could have seen how!) – EightBitTony Jun 17 '11 at 16:41
Aha, can't comment until I have 50 rep :) So, I would love to have just commented, but the site doesn't trust me enough to do that, and the only way to build that trust is to write answers ;) – EightBitTony Jun 17 '11 at 16:53

I agree with the comments before about the lack of information. However read the IBM Redbooks about AIX Performance tuning. This should at least point you in the right direction.

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Welcome to unix.SE! I realize this question doesn't have enough detail to give quality answers, but for future reference we really try to provide answers here that do more than point people in a direction that will point them in a direction. Asking for more information is something to use the comment box on the question for. If this question were answerable we would also want to see a quote or summary of relevant information beyond just the book name. – Caleb Jun 17 '11 at 16:06
Noted. Will ensure future posts give answers. – vegasbrianc Jun 17 '11 at 16:41

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