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

[Lawrence K. Chen, P.Eng.]

Is the FreeBSD system using accf_dns (ACCEPT_FILTER_DNS) ?  If so, perhaps
something like it is needed on RHEL?

On 04/25/14 11:51, Shawn Zhou wrote:
> 
> Looks like BIND 9.9.4b1 has support for SO_REUSEPORT as test results I get
> from RHEL 6.5 look better than what I have from RHEL 6.4:
> 
> https://www.dropbox.com/s/4u1ajqoj16ar7tl/40MB_receive_buffer.png
> 
> I have been wondering why the drop rate is higher in the lower range of QPS in
> FreeBSD (24 UDP BIND listeners) than RHEL 6.5 (16 UDP BIND listeners). Could
> it be that those 24 listeners are handing out queries too fast from the socket
> to worker threads on FreeBSD and those 16 listeners are emptying the receive
> queue at the right speed for worker threads until we hit the peak at ~200k QPS
> on RHEL6.5?
> 
> My tests show 16 listeners on RHEL 6.4/6.5 provides the best performance on
> hosts with 24 and 40 CPU threads. I am not sure why 16 is such a magic number
> ("Sweet 16", I guess).
> 
> Look at 9.10.0b2 release
> notes https://kb.isc.org/article/AA-01142/81/BIND-9.10.0b2-Release-Notes.html,
> ISC will be adjusting the default setting for the number of listeners: 
> 
>   * The default setting for the -U option (setting the number of UDP listeners
>     per interface) has been adjusted to improve performance. [RT #35417]
> 
> 
> Anyone knows what logic will be used?
> On Thursday, April 24, 2014 5:51 AM, Ralf Weber <dns at fl1ger.de> wrote:
> 
>     Moin!
> 
>     On 23 Apr 2014, at 22:09, Jared Mauch <jared at puck.nether.net
>     <mailto:jared at puck.nether.net>> wrote:
>     > Despite using RHEL 6.4, I wonder if 6.5 or hand-building a 3.x series
>     kernel might provide benefits not evident in the 2.6.3x series that RHEL
>     ships.
>     RHEL 6.5 has a kernel with SO_REUSEPORT support. which can improve UDP
>     performance, but AFAIK needs support from the DNS server software. Not
>     sure if bind supports that. Then of course you could use another DNS software.
> 
>     So long
>     -Ralf
> 
> 
> 
> 
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-- 
Who: Lawrence K. Chen, P.Eng. - W0LKC - Sr. Unix Systems Administrator
For: Enterprise Server Technologies (EST) -- & SafeZone Ally