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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Having spoken with Tobi and others at the
LISA08 conference, I’m going to be expanding the chapter on performance
in the book once I’ve run some more tests.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Some main points that come out for
performance improvement seem to be –<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>0) Obviously, MRTG/RRD beats native mode
MRTG by about a factor of 100.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>1) RRDtool 1.3.x has some cool
memory-mapped IO stuff, and cache-hints (under Linux) that should make a pretty
good performance win over RRDtool 1.2.x<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>2) Running MRTG in daemon mode with
Threads (using a big Include:d master.cfg file) will help a lot as well, but
runs the risk of one typo killing everything. At least this is easy to detect,
though. We currently use multiple-MRTG instances with threads for this reason.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>3) Tuning the filesystem cache timeout
(eg, to 5min rather than 20sec) will give big performance gains at the expense
of resilience to data loss on crashing. Should be a win, though. RRD files
are very very hard to corrupt as they are fixed-length.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>4) Mounting with the noatime option can
help but not much<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I will run some tests here on relative performance
when I’ve the time and let people know, if they’re interested.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I believe that (2) may now give a much
larger performance boost than previously as MRTG 2.16.x and RRD1.3.x can work
together with delayed writes and memory-mapped IO to greatly decrease
filesystem IO when run in daemon mode.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Has anyone else done any performance tests
for MRTG covering these (or other) tunable parameters? Please let me know so
we can pool observations and results…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>As far as other Include stuff goes, I’d
like to see something like<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> Include: filename.cfg<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> IncludeAll: */wildcarded*/filename*.cfg<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> IncludeOptional: filename.cfg<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>since this would be backwards-compatible
with previous config files. I could add support to Routers2 pretty easily. No
time for it now, though… Also, typos in the file should probably be
warnings rather than hard errors, and maybe MRTG in daemon mode should
periodically check the ‘last modified’ time on the files or dirs
and re-read the config files if it detects changes (Routers2 already does this
when in caching mode :P ). But I’m drifting off-topic.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Steve<o:p></o:p></span></font></p>
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