Performance differences for recent kernels running forky test.

From: Steven Cole (elenstev@mesatop.com)
Date: Wed Aug 14 2002 - 14:17:10 EST


I ran the following lots_of_forks.sh script for several kernels.

http://people.nl.linux.org/~phillips/patches/lots_of_forks.sh

using time -v sh lots_of_forks.sh

The results for 2.4.20-pre2 and 2.4.20-pre2-ac1 are very different.

2.4.20-pre2:
Command being timed: "sh lots_of_forks.sh"
User time (seconds): 18.15
System time (seconds): 24.96
Percent of CPU this job got: 181%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:23.71

2.4.20-pre2-ac1:
Command being timed: "sh lots_of_forks.sh"
User time (seconds): 28.04
System time (seconds): 53.18
Percent of CPU this job got: 187%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:43.32

I ran this test 8 times in a row with no pause in between
runs. The numbers are System time as reported by time -v.
The test machine is 2-way p3, SMP kernels, configured the
same, no tweaks to /proc/sys/vm.

        2.4.20-pre2 2.4.20-pre2-ac1 2.5.28 2.5.31

1 24.96 53.18 39.91 37.04
2 24.92 52.42 44.91 45.88
3 24.69 50.69 48.63 44.89
4 24.39 51.9 58.12 55.8
5 24.72 46.14 49.81 43.18
6 24.34 47.99 57.62 40.93
7 24.64 52.33 50.42 47.27
8 24.53 52.84 45 36.49

This may be a very unfair benchmark. Or it may show something
worth investigating further.

Steven

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