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Linux, networking and nmon based CPU utilization

Posted on 2014-02-03
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Last Modified: 2014-02-03
I am on a 4 core Linux machin running RHEL

When I run a network intensive load, I see a single thread about 99 percent utilizaed, but all the other threads are empty.

In general, what would cause this behavior.    Most of the time with th esame load, I see the CPU utilization more evenly spread throughout the cores ?

Thanks
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Question by:Los Angeles1
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woolmilkporc earned 2000 total points
ID: 39829703
Could it be that this "network intensive load" communicates via an SSH connection?

If so, then please note that OpenSSH is unable to make use of more than one core.
This is due to limitations of the available cipher modes for encryption.

It seems that the OpenSSH developers will not change this behavior in the future,
due to suspected security issues when making encryption multi-threaded.

People at the Pittsburgh Supercomputing Center seem to have developed patches to create a multi-threaded version of the AES-CTR and other supported ciphers.

http://www.psc.edu/index.php/hpn-ssh

Unfortunately I never worked with this, so I can't help any further if you're inclined to compile your own patched SSH.

wmp
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by:Los Angeles1
ID: 39829752
Actually, its a messaging and sometime App server load
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by:woolmilkporc
ID: 39829819
Do you mean "IBM Sametime"?

I know that Domino is highly multi-threaded, but I have no idea if this is also the case for Sametime, because we don't use it. Sorry.

Here is the Sametime 9 Tuning Guide. maybe it can help.
http://infolib.lotus.com/resources/sametime/9.0/ST900ACD041/en/st9_access_tune.html
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