Ticket #228 (closed defect: fixed)

Opened 6 years ago

Last modified 7 months ago

cpu plugin shows wrong values

Reported by: dz@426.ch Assigned to: janl
Priority: normal Milestone: Munin 1.4
Component: plugins Version: 1.2.4
Severity: minor Keywords:
Cc:

Description

The cpu plugin depends on the correct clock tick (HZ) to calculate the correct percentage values. Unfortunatly the HZ differs from kernel to kernel. I have introduced a HZ configuration variable: 

--- cpu.orig    2006-05-09 14:25:54.000000000 +0200
+++ cpu 2006-05-12 08:21:46.000000000 +0200
@@ -9,6 +9,16 @@
 #      config   (required)
 #      autoconf (optional - used by munin-config)
 #
+# Environment variables:
+#
+#      hz      Number of clock ticks per second (default 1000).
+#              Older linux kernels have 100 instead. Find out the correct
+#              value in /usr/src/linux/include/asm/param.h or execute
+#              (cat /proc/interrupts;sleep 1;cat /proc/interrupts)|grep timer,
+#              subtract the first big numbers and decide if they are
+#              closer to 100 or 1000.
+#
+#
 # $Log$
 # Revision 1.8  2004/12/09 22:12:56  jimmyo
 # Added "graph_period" option, to make "graph_sums" usable.
@@ -49,6 +59,7 @@
 #%# capabilities=autoconf


+hz=${hz:-1000}

 if [ "$1" = "autoconf" ]; then
        if [ -r /proc/stat ]; then
@@ -152,7 +163,7 @@

 if [ ! -z "$extinfo" ]
 then
-       awk '/^cpu / { print "user.value " $2 "\nnice.value " $3 "\nsystem.value " $4 "\nidle.value " $5 "\niowait.value " $6 "\nirq.value " $7 "\nsoftirq.value " $8 }' < /proc/stat
+       awk -v hz=$hz '/^cpu / { print "user.value " $2*100/hz "\nnice.value " $3*100/hz "\nsystem.value " $4*100/hz "\nidle.value " $5*100/hz "\niowait.value " $6*100/hz "\nirq.value " $7*100/hz "\nsoftirq.value " $8*100/hz }' < /proc/stat
 else
-       awk '/^cpu / { print "user.value " $2 "\nnice.value " $3 "\nsystem.value " $4 "\nidle.value " $5 }' < /proc/stat
+       awk -v hz=$hz '/^cpu / { print "user.value " int($2*100/hz) "\nnice.value " int($3*100/hz) "\nsystem.value " int($4*100/hz) "\nidle.value " int($5*100/hz) }' < /proc/stat
 fi

Notes:

  • This patch relates to Ticket 120
  • The "if [ ! -z "$extinfo" ]" branch is not tested due to lack of a 2.6 kernel

Change History

14/06/06 20:41:02 changed by janl

  • owner changed from jo to anonymous.
  • priority changed from high to normal.
  • status changed from new to assigned.
  • severity changed from normal to minor.

I cannot see why this should be needed. The plugin works correcyly on 2.6 kernels with 1000 Hz. Can you please provide more information?

Nicolai

14/06/06 20:41:28 changed by janl

  • owner changed from anonymous to janl.
  • status changed from assigned to new.

22/06/06 21:23:48 changed by janl

  • status changed from new to assigned.

No i386 or x86_64 I have access to (all running 2.6 and using HZ=1000) display this problem but I've finaly gotten my head around the mechanism. Patch in 1034.

28/06/06 12:01:17 changed by janl

The fix gives: 

> fetch cpu
> user.value 3.59307e+09
> nice.value 508709
> system.value 508899567
> idle.value 1467626129

Use printf: 

awk -v hz=$HZ '/^cpu / { printf "user.value %.0f\nnice.value %.0f\nsystem.value %.0f\nidle.value %.0f ", $2*100/hz, $3*100/hz, $4*100/hz, $5*100/hz }' < /proc/stat

07/07/06 18:07:04 changed by dz@426.ch

Typo (by me not janl ;) )

Omit the space after "idle.value %.0f".

Correct is: 

awk -v hz=$HZ '/^cpu / { printf "user.value %.0f\nnice.value %.0f\nsystem.value %.0f\nidle.value %.0f", $2*100/hz, $3*100/hz, $4*100/hz, $5*100/hz }' < /proc/stat

25/08/06 00:37:57 changed by janl

  • status changed from assigned to closed.
  • resolution set to fixed.

Alright, think I got it all now. Revision 1048.

27/10/11 11:45:43 changed by puncvirecberg1973

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