mmap vs alloc
arnt at gulbrandsen.priv.no
Thu Sep 25 11:15:19 UTC 2003
Jaap Akkerhuis writes, quoting me:
> It's better to mmap() and pray that the file isn't changed, than
> to read() and pray that overcommit won't explode.
> Seeing this discussion and being agnostic, it seems to me that this
> has more to do with the operating environment (amount of data served,
> operating system used etc.) then with nsd itself, praying is not an
If the nsd admin is in a position to guarantee that nsd.db is never
edited, mmap() is fine.
To do that, write access to nsd.db must be tightly controlled and zonec
must use e.g. "open(); write(); close(); rename()" in order to build
the new database without touching the old one. So, root passwords
carefully controlled, no stray users with write access to the nsd
> My suggestions is, that a proper thing to do is to document that nsd
> has specific memory requirements (lots) and how the various system
> might deal with it or not.
How many linux 2.4.x kernels have contained sweeping VM changes so far?
The one mentioned this week was a prepatch, even. I don't think
"document how various systems might deal with it" is a good policy when
the _stable_ linux kernels change like that.
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