Interesting series Part 2: Understanding Linux Load Average
Originally posted on The Dutch Prutser's Blog:
In part 1 we performed a series of experiments to explore the relation between CPU utilization and Linux load average. We came to the conclusion that CPU utilization clearly influences the load average. In part 2 we will continue our experiments and take a look if disk I/O also influences the Linux load average.
Disk I/O and load average
The first experiment is starting 2 processes performing disk I/O on an otherwise idle system to measure the amount I/O issued, the load average and CPU utilization using the
sar command. BTW: My
load-gen script uses the
dd command to generate disk I/O.
-b command line option given to
sar tells it to report disk I/O statistics. The above output tells us that on average 48207 blocks per second were written to disk and almost nothing was read. What effect does this have on the load average?
The run-queue utilization…
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