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When I did a 'top' command on my SUSE 11 sp1 system, I noticed that command telnet is 88% CPU. Sometime I saw 99% cpu. My understanding is this is ...
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  1. #1
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    When I did a 'top' command on my SUSE 11 sp1 system, I noticed that command telnet is 88% CPU. Sometime I saw 99% cpu. My understanding is this is what is used at the point in time when top is getting the data. But should I be concern about this?

    I also see
    Cpu(s): 35.0%us, 64.9%sy, my understanding of this is kernel is using 64.9% of CPU and User is using 35%. This adds up to be 99.9%. Does it mean CPU usage is 99.9% at that point in time ?

    me@server0001:~> top
    top - 16:12:57 up 11 days, 11:06, 6 users, load average: 7.37, 7.47, 7.51
    Tasks: 232 total, 8 running, 204 sleeping, 0 stopped, 20 zombie
    Cpu(s): 35.0%us, 64.9%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st
    Mem: 8064932k total, 7878900k used, 186032k free, 154292k buffers
    Swap: 8388600k total, 75776k used, 8312824k free, 1664272k cached

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    2153 root 20 0 8592 712 544 R 88 0.0 1482:51 telnet
    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    2153 root 20 0 8592 712 544 R 88 0.0 1482:51 telnet

  2. #2
    Linux Engineer docbop's Avatar
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    High numbers are no big deal in short spurts, what you don't want is 95%+ sustained for long periods.
    A lion does not lose sleep, over the opinion of sheep.

  3. #3
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    IMO these days the fact that "telnet" is running at all is odd. That it's consumed a significant amount of CPU and is running as "root" is unusual as well. Any idea why there are "telnet" clients running on the system?

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    "Does it mean CPU usage is 99.9% at that point in time ?"

    To be sure, look at the %id. The percentage idle can help you. You could do some random tests throughout the day (especially when the server has a load on it). If you wanted to be proactive, you could create a script to gather statistics.

    It isn't uncommon for servers to spike their CPU utilization. But as a previous post said, if this is common, you have an under-powered server. Or possibly the code on the server was written poorly. Optimization should follow if this is common. Using more hardware (better CPUs, more cores) or tuning the jobs (when they run, what they process) would be next steps.

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