Quation about HZ kernel option
olli at lurza.secnetix.de
Thu Oct 4 05:34:03 PDT 2007
Artem Kuchin <> wrote:
> What value of HZ option would you recommend
> for a hosting (web) server with a lot of processes
> (about 900) and polling off (as decided from previous
> discussion polling is useless in
> this situation).
In that case, I would recommend not to override the
default at all (which is 1000).
> What parts of kernel does this option affect? What
> depends on it?
The value of HZ specifies the minimum timing quantum
of the kernel. It affects the granularity of the
scheduler and all timing-related functions (nanosleep(2)
and others), and the accuracy of dummynet and polling.
I'm sure there are more things.
Basically, the kernel cannot handle time slices smaller
than 1/HZ seconds, for any purpose.
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