slow performance in guest Redhat Linux on VMware ESX

Posted on 2008-11-03
Last Modified: 2013-12-06
While running this script,
while [[ i -le $1 ]]
on a few RedHat 4 virtual guest machines, we noticed several different response times.  The worst case was on a guest OS which took over 40 seconds, whilst several other guest machines averaged around 4 or 5 seconds.  Would anyone be able to suggest the reason for such a wide discrepancy?

The slow machine runs on an ESX host with 4x3GHz Xeon cpu's, 30 GB of memory.  This physical host also runs 2 other guest systems, but all were relatively idle at the time of the test.  

On the slow machine, vmstat every 10 secs shows high cpu consumption (for such a simple script) and no memory shortfall (no swapping):

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 2  0      0 1444928 100896 402204    0    0     0     2 1011   104 51 21 28  0
 4  0      0 1443488 100896 402204    0    0     0    59 1017   217 75 25  0  0
 0  0      0 1446960 100896 402204    0    0     0    38 1014     93 34  9 57  0
 1  0      0 1447104 100896 402204    0    0     0    12 1012     89   7  2 91  0 <- end of test.

Any ideas much appreciated.

Question by:jainesteer

    Author Comment

    Update: I should have mentioned that the timings were for counting up to 100,000 with the script.
    LVL 10

    Expert Comment

    does the guest have vmware-tools installed ?

    Author Comment

    On the vmware infrastructure client for this guest OS, it says VMWare Tools: OK.  
    But "VMwareTools" is not in the guest OS rpm list.

    Author Comment

    Ran vmware-tools on the guest (sorry, not used to vmware) and got version 3.5.0 build-110268.  
    LVL 10

    Expert Comment

    just right clicked on the guest on the virtual center or did an rpm -ivh of the vmware-tools rpm ?
    follow this document to make sure you've done the whole thing...

    and repeat the tests with the vmware tools service on

    Author Comment

    On the guest OS, the vmware service is already running ...

    # service vmware-tools status
    vmware-guestd is running
    # ps -ef | grep -i vm
    root      2625     1  1 Nov01 ?        00:53:02 /usr/sbin/vmware-guestd --background /var/run/
    # cat /var/run/

    So the performance test was run with the vmware tools service on.  I tried turning it off and back on again, but there is no difference in performance.

    Accepted Solution

    Problem resolved: the guest system was booting up with the ELhugemem Linux kernel instead of ELsmp. Set ELsmp as default in /etc/grub.conf and reboot.   Performance now normal!

    Thks for your replies.

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