[collectd] collectd versus rrdcollect-remote rrdtool [network] IO

Greg greg at easyflirt.com
Wed Jan 21 15:27:09 CET 2009

Hi Florian,

> okay, this shows that the default value of 124928 was not sufficient. So
> that was one source. If the machine isn't doing much else (doesn't have
> a ton of other sockets), it shouldn't be a big problem to increase this
> value even further. The 4 MBytes (4194304 bytes) I've mentioned earlier
> have worked well for my setup.

I'm trying with 8M and it works, no more missing values.
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216

> Sounds okay, though if you expect your installation to grow, you may
> want to invest in some RAM. When all RRD files together are
> approximately the amount of RAM you have, that's when stuff tends to
> become difficult, so buying another 4gig might be the easy way out ;)

I have 8GB spare memory, and going to add them this afternoon.

> Uh oh, not good. Try mounting the partition, the RRD files are on, with:
>   -o noatime,nodiratime,commit=120
> This alone should improve performance considerably.

I have to restart to add the 8GB, so I have added this mount options. 
But those options was not mandatory for my old config with rrdcollect + 
a big database...

> So how's your system handling the load otherwise? How much time is spent
> in IO-wait? (Should be close to 12.5% with 8 CPUs.) Do you have any gaps
> in the ``local'' data, i. e. the data that was not sent over the
> network?

All time is spent in IO...

> What I'd be most interested in: Does commit 0b6de87f [0] really improve
> performance, or was this a wrong guess?

Will try if I have some time.


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