[rrd-users] Can this script be optimised ?
linux at thehobsons.co.uk
Wed Nov 28 17:27:32 CET 2012
Pablo Sanchez wrote:
>When I do any optimization, I always instrument and prioritize the
>slowest area of code.
>Looking at the shell script below, there appear to be two areas of
>optimization that you can change:
>1) The while conditional check, and/or
>2) The setting of UpdateVal
>I'll assume the `rrdtool' can't be changed (e.g. the disk the .rrd is
>on isn't the bottleneck.
>Given the above, where's the slowness? Is it 1) or 2)?
I assume the main bottleneck is forking processes - as you hint,
there's a fork for the while check, and then several forks to
get/update the values (I'd expect all the code/external programs to
remain in cache as there's spare RAM). The code runs OK, and I
estimate that it takes about 2.5% of the CPU - based on using 'time'
to get the system and user times for a complete run and dividing by
The runtimes for those two bits are :
To get the value :
To run the update (which goes to a remote system, it's not a local RRD file) :
It's not so much optimising individual bits, it was more a question
of "does a fresh set of eyes see something that shouts out "that's an
inefficient way of doing it'". I'd already spotted several areas
where I was able to improve the code when I came back (after a year
or two since I first wrote it) and took another look.
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