I'd like to thank those who helped me to accomplish this feat. After a
lot of head pounding and squinting at some of the proc files funny, I
get it working and accomplished a lot of the goals that I had. The idea
was to have a very unobtrusive way to get instant cpu usage and possibly
memory info. I wound up using three separate shell scripts and offloaded
most of the work to the master node which is dedicated to this kind of
stuff.
mystat.sh (each node accesses this script)
#! /bin/bash
stats=(`head -n 1 /proc/stat`)
((prev=${stats[1]} + ${stats[2]}))
sleep 3
stats=(`head -n 1 /proc/stat`)
((now=${stats[1]} + ${stats[2]}))
((total=($now-$prev)))
tmp=(`cat /proc/meminfo | grep MemTotal`)
memstat[0]=${tmp[1]}
tmp=(`cat /proc/meminfo | grep MemFree`)
((memstat[1]=${memstat[0]}-${tmp[1]}))
tmp=(`cat /proc/meminfo | grep SwapTotal`)
memstat[2]=${tmp[1]}
tmp=(`cat /proc/meminfo | grep SwapFree`)
((memstat[3]=${memstat[2]}-${tmp[1]}))
echo $total ${memstat[0]} ${memstat[1]} ${memstat[2]} ${memstat[3]}
mystat_c.sh (since the nodes don't have bc the master node does the
"high level" math)
#! /bin/bash
ticks=$(rsh $1 /usr/local/bin/mystat.sh)
stats=(`echo $ticks`)
percent=$(echo "scale=1; ${stats[0]}/6" | bc)
mem=$(echo "scale=1; ${stats[2]}*100/${stats[1]}" | bc)
swap=$(echo "scale=1; ${stats[4]}*100/${stats[3]}" | bc)
echo "$1 ${percent} ${mem} ${swap}"
mystat_s.sh (runs mystat_s.sh for each node and redirects output)
#! /bin/bash
mv stats.out.new stats.out
for i in `seq -f "%02g" 01 65`;
do
/var/www/mystat_c.sh beast$i >> stats.out.new &
done
I have this running as a cron job every minute and then the web page
looks for the stats.out file and parses it. If anyone else wants to
calculate the cpu utilization from the proc file, take the difference of
the jiffies and divide by the number of procs times the time difference
(if you use the summary line). That took me a long time to figure out
(it's always the easy things!), but it matches pretty close to what top
reads and doesn't have such a performance hit for a single 3 sec read.
The final product: http://babeast.byu.edu/screenshot.jpg
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