better performance with 32 bit ! why?

[Eivind Olsen]

iharrathi.ext at orange-ftgroup.com wrote:

> Is it normal that bind when compiled and installed on a 32 bit server have
> better performance than bind when compiled and installed on a 64 bit
> server.
> the only différence between the two server is 64 bit vs 32 bit ( same RAM,
> same Disk, same NIC,...) and CPU is better on the 64 bit (2 Intel E5310
> quad-core 1.6Ghz) than the 32 bit(2 Intel Xeon duad-core 2.33Ghz).

I'll admit I haven't really done any proper benchmarking of BIND on 32 vs
64 bit systems. I have done some benchmarking before though.
You're doing the exact same queries, asking for local / locally cached
data? Just so I know that you're _really_ comparing apples to apples. The
systems are configured exactly the same, also with regars to which other
services might be running there, SELinux settings, iptables etc?

In my experience: yes BIND9 is multithreaded, but there seems to be very
little (if any) gain from letting it use more than 4 CPU cores / threads,
meaning the 32 bit 2.33GHz CPU might actually win out purely based on the
higher clock frequency.

Also, you mentioned you were seeing a similar picture when using tcpreplay
- as far as I know tcpreplay is single-threaded - which also suggests the
reason it might win out on the 32 bit system is again due to the clock
frequency.

Regards
Eivind Olsen