rmap ovflo messages

[Bertus Stuiver]

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?

[Andy Monks]

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.

[melvyn burnard]

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

[Magnus Lundström]

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]

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

[Vincente Fernandes]

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