Red Hat Bugzilla – Bug 118647
kswapd in state R and D load constant at 1+
Last modified: 2007-11-30 17:07:00 EST
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Description of problem:
After Upgrading to the 2.4.21-9.0.1.EL kernel (WS) two machines have a
constant load of 1.00 when they're idle. Didn't have these issues with
top is showing kswapd being either in state R or D. No other processes
seem to be running.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Boot machine
2. Look at the output of top
Actual Results: load is constantly at +1 even if machine is idle
Expected Results: load is nearly at 0 if machine is idle
Created attachment 98653 [details]
Output of "top -b -n 1"
Created attachment 98654 [details]
Output of lsmod
Take a look at https://bugzilla.redhat.com/bugzilla/show_bug.cgi?
I think this was caused by our setting the
/proc/sys/vm/inactive_clean_percent too low in the RHEL3-U1 update.
Please try "echo 30 > /proc/sys/vm/inactive_clean_percent and let us
know it this helps.
We experienced the same problem with a x445 with 16GB ram and
changed /proc/sys/vm/inactive_clean_percent to 30 (as described in
bug 115438), which actually did help.
Because I have read in another bugreport that setting this value to
100 is the solution, I would like to know what the correct value is
(does it depend on the amount of ram and if so, what's the rule to
roughly calculate the best value?) and how it influences the system?
Are there other parameters which default values are not set as good
as they could be?
Is there a documentation where one can find out more about the magic
world of kernel-parameters?
"Echoing" 30 did help. The load on both machines dropped to zero.
Thanks for the quick help!
You want 30 and not 100. I probably told you to set it to 100 to
quickly verify that it was causing your problem. In the latest kernel
update we changed the default value from 5 to 30 because it was too
low for many systems so it will no longer need to be adjusted.
Thanks a lot for your immediate reply.
However, can you give me a hint where to find info / documentation
about the various kernel-parameters or about those, which should /
can be adjusted?
As far as I've seen, the documentation in the kernel-
source /usr/src/linux/Documentation is not really always up to date.
I'm setting this to "modified" because the U2 kernel has been
changed to use a default inactive_clean_percent value of 30.
As for where to find further info about VM tuning, I'll let
Larry follow up on that question.
I've got this whitepaper that may help out here:
An errata has been issued which should help the problem described in this bug report.
This report is therefore being closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files, please follow the link below. You may reopen
this bug report if the solution does not work for you.