[nsd-users] NSD 4.1.18rc1 pre-release

[Paul Wouters]

On Thu, 16 Nov 2017, W.C.A. Wijngaards wrote:

>>> This release has features for saving memory and faster notification.
>>> With --enable-packed, 33% memory savings could be had, or something
>>> along that size.  Notification of secondary servers happens in parallel,
>>> and has faster timeouts.  More sockets are used for zone transfers.
>>> This speeds up communication with a larger set of servers.
>>
>> What is the downside of this option? I assume there is one, because
>> otherwise this would not be a compile time option?
>
> Packed structures are more difficult to access by the compiler.  It is
> likely that the compiler needs to generate more code to access members
> in the data structure.  The assumption that data is aligned in memory is
> not there.  The compiler will generate different code.  Because it is
> packed, it'll use less memory, but that code also has to be executed.  I
> don't know what the speed impact is, if any.

Okay, so that does not really help me to determine:

>> I'm trying to make the determination for RHEL/CentOS/Fedora on whether
>> I want this compile time option enabled or not.

which I guess is why this is a compile time option :)

Paul