KernelTrap: Changing The Default Hertz

“A recent discussion on the lkml debated the merits of modifying
the default hertz of the Linux kernel. The default hertz of the 2.4
kernel is 100 Hz, while the default hertz of the 2.6 kernel is
currently 1000 Hz. In Andrew Morton’s plans for 2.6.13 he lists a
patch tagged with the comment, ‘changes default HZ to 250, make HZ
Kconfigurable.’ As to why 250Hz was chosen, Linus explained in an
email from May of 2004, ‘1kHz is also good in that it makes it easy
to convert both to USER_HZ and to ms/ns. But maybe something like
250Hz would be better–still high enough that things like
multimedia (which really wants higher frequencies in order to be
able to sleep for fractional video-frames) should be happy, low
enough that we use less CPU…'”

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