[dns-operations] BIND performance difference between RHEL 6.4 and FreeBSD 7

Mark Delany x2t at foxtrot.emu.st
Tue Apr 29 23:00:43 UTC 2014


On 29Apr14, Lawrence K. Chen, P.Eng. allegedly wrote:
> Is the FreeBSD system using accf_dns (ACCEPT_FILTER_DNS) ?  If so, perhaps
> something like it is needed on RHEL?

I'd be surprised. accf_dns only works for TCP and it only helps if the
(typically very short) request is fragmented.

It's not clear to me that context switches are the biggest cost in the
UDP path to user space, more so just the cost of getting the packet up
thru the network stack.


Mark.



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