BIND 8.1.2 on solaris7 X86 Secondary DNS server
Mark_Andrews at isc.org
Mark_Andrews at isc.org
Mon Oct 25 14:11:03 UTC 1999
> Mark_Andrews at isc.org wrote:
> >
> > We fixed a number of DoS issues with BIND 8.2.2 this may be one
> > of them. It may also just be resource starvation. BIND does not
> > behave well in an envirionment where there is swapping / paging
> > occuring.
> >
> > Mark
> >
>
>
> Please explain in a bit more detail, what you mean by the above. I run
> under Solaris 2.x which swaps/pages regularly and have noticed
> degradation in my name services. I would like to know whether or
> not your observations apply to my situation.
In general there is no locality of reference between seqential
queries to a nameserver or between when the internal tree is
stored and the data hanging off it. This results in almost the
worst possible memory access patterns for a VM subsystem that
is short of physical memory as the page that was just freed is
the one likely to be needed next.
On top of that names periodically has to walk the entire tree
to free up resource records that have expired. The creates a
working set of pages which encompass the whole memory image.
If there is not enough memory to hold the whole image in physical
memory at one time performance goes through the floor.
Named is designed to handle thousands of queries per second. You
don't get that speed unless most of the queries are answered from
memory.
One of BIND 9 design goals is to improve this behaviour.
Mark
>
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--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
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