[rrd-users] starting at 1970 / Pipe error / Absolute seconds on X-axis

Cheng Hu chenghu at ugcs.caltech.edu
Sat Aug 10 20:54:39 MEST 2002


Problem 1

This may seem absurd but I have a need to specify --start 0 or some small
number with rrdtool create. That is, I want it to start timing from 0 or 1
seconds after 1970. However if I specify 0 or 1, the start time defaults
to now. If I specify 100 say, I get an error message asking if I meant
month 100 instead, but I don't. (If you really want to know why I need to
do this, I've included it at the end)

Problem 2
I would like to control rrdtool from a C program. The way I am doing it
now is using rrdtool's remote control feature. I fork a process to exec
rrdtool, and make a pipe from the controlling program to the rrdtool
program's stdin. Then I use fprintf with the pipe to issue commands.

While this is working for small amounts of data, I get a pipe error signal
if I input a lot of data too fast, which I need to do.

Is there a more efficient way to control rrdtool from C? If not, does
anyone know how I can avoid this error?

Problem 3
I'd like to display seconds since 1970 on my x-axis, but no strftime
format will let me do it. Is there a way?

Thanks and regards,
Cheng Hu

(Reason: I am running of network stack monitoring program that I wrote
that generates data on microsecond resolution, and generates a lot of
data. I'd like to graph this using rrdtool (is there a better tool for
this purpose?) so I convert microseconds to second, and seconds times
1000000. To avoid overflow, I need to start from time 0)

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