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rmap ovflo messages

Bertus Stuiver
Occasional Advisor

rmap ovflo messages

Since we run oracle 8.0.6 at HP-UX 10.20
i'm getting 'rmap ovflo' messages in my syslog and dmesg bufffer.

Does anyone know if this can be related to
oracle?
5 REPLIES
Andy Monks
Honored Contributor

Re: rmap ovflo messages

It's pure hp-ux memory management. You may want to double the nproc kernel parameter (or double maxusers which is a macro used by default in nproc).

Either way not directly Oracles fault (although it may be responible for hp-ux fragmenting it's memory.

Re: rmap ovflo messages

You could also experience this problem if your nfile parameter is very high.
You should monitor this symptom, as if it gets too bad you could end up with a system panic with the string:
kalloc: out of kernel virtual space
My house is the bank's, my money the wife's, But my opinions belong to me, not HP!
Magnus Lundström
Occasional Advisor

Re: rmap ovflo messages

This may also be solved by patches if your system is using super pages. To check if you are using super pages do this:

echo cpu_has_var_size_pages/D | adb /stand/vmunix /dev/kmem

Output:
cpu_has_var_size_pages:
cpu_has_var_size_pages: 0 or 1 <---

If the result is 1 you can install PHKL_16751 + dependencies to address this problem.
Stefan Farrelly
Honored Contributor

Re: rmap ovflo messages


go to the "Search Technical Knowledge Base" and search for the string KBRC00000293, it explains in detail the problem and solution.

We run the following script on our 10.20 servers to keep an eye on the sysmap level, if it starts to get low we get an alarm and we know to increase maxusers.

#!/usr/bin/sh
# a crude tool to monitor sysmap fragmentation
# print warning to stderr if less then WARN percent of
# sysmap entries are free, or no chunk of size MINCHUNK available
# WARN=10 and MINCHUNK=50000 are guesses only, no scientifically
# determined default values
# may be adapted to 9.X (but why?), possibly to read dumps
# or other maps
typeset -i WARN=10
typeset -i MINCHUNK=50000
ADB=/usr/bin/adb
OPT="-k /stand/vmunix /dev/kmem"
get_one_value()
{
echo "$1"|$ADB $(echo $OPT)|awk -F: '/[0-9]/
{print $2}'
}
typeset -i SYSMAP=$(get_one_value sysmap/D)
typeset -i SYSMAP_END=$(get_one_value "sysmapNSYSMAP/D")
typeset -i SYSMAP_END1=$(get_one_value "0d$SYSMAP/D")
if [ $SYSMAP_END -ne $SYSMAP_END1 ]; then
echo $0: Unable to determine size of sysmap -
exiting >&2
exit 1
fi
(( MAPSIZE = ( SYSMAP_END - SYSMAP ) / 8 ))
(( MAPLINES = MAPSIZE - 2 ))
(( SYSMAP = SYSMAP + 8 ))
typeset -i FREE=0
(echo "0d$SYSMAP/2D"; yes "" | head -n $MAPLINES)
| $ADB $(echo $OPT) |
awk ' { if ( ($2 == 0) && ($3 == 0) )
{ FREE = FREE + 1 }
else { FREE = 0 }
if ( $2 > MAX ) { MAX = $2; }
}
END { print FREE, MAX } ' |
read FREE MAX
echo $FREE of $MAPSIZE entries in sysmap are free
echo maximum available chunk size is $MAX
typeset -i PCT=0
(( PCT = ( 100 * FREE ) / MAPSIZE ))
if [ $PCT -lt $WARN -o $MAX -lt $MINCHUNK ]; then
if [ $PCT -lt $WARN ] ; then
echo $0: Warning: less than $WARN percent of sysmap are free
>&2
fi
if [ $MAX -lt $MINCHUNK ]; then
echo $0: Warning: no chunk of size $MINCHUNK in sysmap >&2
fi
exit 1
else
exit 0
fi
Im from Palmerston North, New Zealand, but somehow ended up in London...
Vincente Fernandes
Valued Contributor

Re: rmap ovflo messages

run "sar -v" and it should show as below:
Check the values of proc-sz: it will tell you what is the current# of process.
00:00:01 text-sz ov proc-sz ov inod-sz ov file-sz ov
01:00:00 N/A N/A 205/2000 0 868/6300 0 455/6010 0
we had a similar problems a few of our servers and got fixed by increasing the nproc