[nsd-users] understanding memory issues

Klaus Darilion klaus.mailinglists at pernau.at
Mon Jul 2 16:11:55 UTC 2018

Hi Wouter!

Am 02.07.2018 um 15:26 schrieb W.C.A. Wijngaards:
> Hi Klaus,
> On 02/07/18 15:24, W.C.A. Wijngaards wrote:
>> Hi Klaus,
>> On 02/07/18 15:01, Klaus Darilion wrote:
>>> Hi!
>>> We use NSD 4.1.6 as slave for a large zone (2G zone file). It seems
>>> sometimes the memory is too short:
>> NSD tries to recover from the cannot allocate memory failure by
>> performing the update again.  But I guess this also fails (for the same
>> reason?).  Linux has kernel settings on memory overcommit that allow you
>> to bypass these limits; since NSD shares most of the memory, also after
>> fork, and this is not the default assumption of the virtual memory
>> overcommit heuristic.  But you don't really need to set it I think,
>> because you can save memory with database: "" and by upgrading.

We already use database: ""

>> With NSD 4.1.6 in use one solution is update to the latest, 4.1.22.  Set
>> database: "" in nsd.conf, that saves about half memory.  Then with the
>> version upgrade, you can save half memory again on that result, by
>> --enable-packed at compile time and the selective nsec3 allocations.
> Oh and I missed that in 4.1.13 introduced another 15% memory savings
> with the --disable-radix-tree configure option.  You can use that option
> on top of the previous options.  I guess that is likely to solve the
> fork failed: cannot allocate memory error.

Couldn't you make these features enabled with a config option.
Rebuilding is complicated and usually I want to stick with the versions
coming with the Linux distribution.


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