Hello, I've noticed the same strange load calculation inconsistency while running kernel 2.6.32-30. Load values are reported too low for given CPU utilization. As far as I remember older kernels from 2.6.32 line had also the same problem. I did some tests on the same hardware using 2.6.26-26lenny2 and 2.6.30-6 kernels, but their load seems to be just right.
What's more puzzling is that load is reported correctly on 2.6.32 when CPU cores are used in 100%, e.g. running: # stress -c 4 reports load 4 when 4 cores are quite busy. However running about 80 php-cgi processes when idle is greater than 20% (a rough estimation) results in this load calculation error. I did some searching and found similar bug report on Launchpad: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/513848 and a discussion on LKML: http://lkml.org/lkml/2010/4/13/394 The patch proposed on LKML is the one that got applied to Ubuntu's kernel version 2.6.32-20.29. I've patched the Debian's 2.6.32-30 and it seems that load values are correct, although still a bit lower than on other kernels. Tests were run on simultaneously different servers (same hardware and same jobs run) and I was getting similar results when I switched kernels between machines. *** 2.6.26-26lenny2 # vmstat 10 4 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 4 0 0 5540920 0 651616 0 0 0 0 102 277 24 2 73 0 7 0 0 5541300 0 651616 0 0 0 0 4098 12131 23 3 75 0 1 0 0 5546456 0 651616 0 0 0 0 4032 11665 23 2 75 0 0 0 0 5545568 0 651616 0 0 0 0 3646 10950 25 2 73 0 # cat /proc/loadavg 2.82 2.99 2.94 1/240 24960 *** 2.6.32-30 # vmstat 10 4 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 0 0 5521764 0 676944 0 0 0 0 62 131 27 3 71 0 6 0 0 5523952 0 676944 0 0 0 0 8339 16585 21 2 76 0 2 0 0 5525632 0 676944 0 0 0 0 9603 19163 31 3 66 0 6 0 0 5525188 0 676956 0 0 0 0 9474 17614 31 3 66 0 # cat /proc/loadavg 0.05 0.14 0.28 8/284 13343 *** 2.6.32-30 (patched) # vmstat 10 4 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 0 0 5504608 0 657820 0 0 0 0 24 53 26 2 72 0 0 0 0 5507128 0 657820 0 0 0 0 8530 17326 23 2 75 0 6 0 0 5508288 0 657824 0 0 0 0 8634 17051 26 3 72 0 4 0 0 5506352 0 657824 0 0 0 0 9139 18106 27 3 70 0 # cat /proc/loadavg 2.31 2.10 1.94 5/284 12602 -- System Information: Debian Release: 5.0.8 APT prefers oldstable APT policy: (500, 'oldstable') Architecture: amd64 (x86_64) Kernel: Linux 2.6.32-5-amd64 (SMP w/8 CPU cores) Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/bash -- Lesław Kopeć Administrator email: leslaw.ko...@nasza-klasa.pl tel: +48 519 300 129 Nasza Klasa Sp. z o.o. ul. Gen. J. Bema 2, 50-265 Wrocław Sąd Rejonowy dla Wrocławia - Fabrycznej we Wrocławiu, VI Wydział Gospodarczy Krajowego Rejestru Sądowego, nr KRS:0000289629, NIP:898-21-22-104, REGON:020586020, Kapitał zakładowy: 67 850,00 PLN
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