I've used a large collection of PCs running somewhat real-time network
analysis with a HZ set at 5000Hz with absolutely no ill effects (this
was with P-III-450's)
using HZ=10000 was outside of the possibilities of the machines.
one big gain is with timing, which will be better (I myself used NTP to
have a coherent timing on the collection of PC's, with an
inter-correlation better than 1 ms)
TfH
Eugene Panchenko wrote:
>
> Hello!
>
> I've seen various postings on the Net where people reported
> network-related and overall performance improvements caused
> by settig HZ kernel option to 1000 (for example), that is,
> reducing a tick size to 1ms for their FreeBSD and Linux
> systems. However, several problems seem to arise, such as
> some device drivers do not include HZ in calculating their
> timeout value, but simply assume HZ to be 100, and also some
> utility programs such as top or ps take timing information
> from the kernel in ticks, also assuming 10ms ticks, however,
> most of these saying were related to Linux. How safe it is
> to bump up HZ to, say, 1000 in FreeBSD (I use 4.5-STABLE)?
> What pitfals will I encounter (drivers, top/ps)? Is there
> are going to be [promised] performance increase? Do I
> really need it? Thank you.
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