better performance with 32 bit ! why?

Michael Graff mgraff at
Wed Jun 29 21:23:01 UTC 2011

Hash: SHA1

On 6/29/11 3:00 PM, Sven Eschenberg wrote:
> One thing that just popped up my mind:
> Does it increase performance, when you, let's say, bind multiple IPs to
> the same NIC and make bind listen to all of those IPs, while of course
> taking care to fix the corresponding NS RRs to contact all of thos IPs.

In general, yes.  If the NIC can handle the data flow well, and the OS
kernel can handle the multiple UDP sockets well.  I've seen some people
"work around" BIND 9's implementation by using 3 sockets on the same
host, either on different IP addresses or on different ports, and use an
external load balancer to make them appear as a singe entity to the
outside world, as well as allow them to be used directly if on different

ISC is addressing this limitation.  It's pretty clear more cores are in
our future, not more CPU per core.  *hugs his 8-core 3.00 Ghz Xeon box*  :)

A lot of work has been done in TCP-land to enable web applications, and
this means UDP has somewhat fallen to the wayside.  After all, there
aren't a lot of applications that use UDP and really expect high data
rates, right?  :)

I've seen some kernels (to remain nameless) that use one giant lock for
all UDP input in the kernel, and while this is a short-lived lock, it is
a contention point.  If listening on more than one socket still has this
bottleneck there isn't much to do about it.

- --Michael
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