Reading can do the same thing as updating. For instance try the following to allocate about 10 MB of memory and actually keep it active: 
perl -e '$_ = "x" x 10_000_000; $_ .= "y"; sleep 1 while /y/;'

[download]
Update: kyle caught a typo where I switched variable names. Fixed.

In reply to Re^2: How to generate 'fake' memory load? (hogs) by tilly
in thread How to generate 'fake' memory load? by unix_95054

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