[rrd-developers] implementing portable format

kevin brintnall kbrint at rufus.net
Mon Nov 3 03:44:40 CET 2008

On Sun, Nov 02, 2008 at 12:42:13PM +0100, Sebastian Harl wrote:
> > 
> > * UPDATEV support?  It would require the daemon to keep a copy of the RRD
> >   header of each file in memory, and perform the same calculations that
> >   will ultimately be performed on the real file.
> > 
> >   - higher memory utilization
> Do you know any numbers for that? I suppose that this would have a
> fairly large impact on large setups. I'd prefer to be able to use the
> available memory to be able to cache real data instead of being able to
> use UPDATEV. So, if this should be implemented, imho it should be made
> optional. I'm not sure though if that's worth the effort though as that
> would presumably add quite some complexity.

Agreed it should be made optional once implemented..  We wouldn't want the
daemon caching a lot of RRD headers if the users never used UPDATEV.

> (Disclaimer: I did not really follow that, so I might repeat stuff or
> just talk plain bullshit - if so, please tell me ;-))

Check my previous email on the thread and let me know if you still have
questions about the BATCH protocol.  The current implementation is
documented in rrdcached.pod.

> I suppose, the goal is to be able to run a series of commands in a row
> with a high update rate but _not_ to be able to continuously run
> commands forever.

The goal with BATCH is to reduce the number of read()/write() syscalls
required when updating files.  This enables updates at a very high rate
(I'm getting > 100k/sec even on 5yo hardware).

 kevin brintnall =~ /kbrint at rufus.net/

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