[rrd-developers] rrdtool 1.3 update slowness

[Evan Miller]

Disabling MMAP in 1.3 makes things worse:

Create     10 rrds      1 c/s (0.00427 sdv)   Update     10 rrds   22975 u/s (0.00013 sdv)
Create     10 rrds      1 c/s (0.00428 sdv)   Update     20 rrds   19045 u/s (0.00087 sdv)
Create     20 rrds      1 c/s (0.00826 sdv)   Update     40 rrds   12433 u/s (0.00205 sdv)
Create     40 rrds      5 c/s (0.03187 sdv)   Update     80 rrds      15 u/s (0.06627 sdv)
Create     80 rrds      1 c/s (0.03359 sdv)   Update    160 rrds      15 u/s (0.06745 sdv)
Create    160 rrds      5 c/s (0.15173 sdv)   Update    320 rrds      13 u/s (0.11210 sdv)

I know very little about IO, so I have no idea what's going on. Let me know if
there are other tests I can run, or if anyone can reproduce the behavior.
Perftest is here:

http://oss.oetiker.ch/rrdtool/pub/contrib/perftest.zip

Thanks,

Evan

On Tue, Aug 28, 2007 at 04:17:47PM -0700, Evan Miller wrote:
> I ran Tobi's perftest.pl against RRDtool 1.2 and the current subversion 
> checkout. Updating a single RRD is noticeably faster under 1.3, but 
> performance grinds to a halt on my machine once I get up to 100 or so 
> RRDs. I consistently produce results similar to these:
> 
> 
> RRDtool 1.2:
> 
> Create     10 rrds      1 c/s (0.00117 sdv)   Update     10 rrds   23288 
> u/s (0.00002 sdv)
> Create     10 rrds      1 c/s (0.00062 sdv)   Update     20 rrds   21125 
> u/s (0.00065 sdv)
> Create     20 rrds      1 c/s (0.00125 sdv)   Update     40 rrds   23385 
> u/s (0.00002 sdv)
> Create     40 rrds      1 c/s (0.00259 sdv)   Update     80 rrds   23150 
> u/s (0.00005 sdv)
> Create     80 rrds      3 c/s (0.41032 sdv)   Update    160 rrds   22688 
> u/s (0.00006 sdv)
> Create    160 rrds     10 c/s (0.02412 sdv)   Update    320 rrds   19940 
> u/s (0.00124 sdv)
> Create    320 rrds      5 c/s (0.02459 sdv)   Update    640 rrds   17601 
> u/s (0.00142 sdv)
> Create    640 rrds      3 c/s (0.04289 sdv)   Update   1280 rrds   10012 
> u/s (0.00432 sdv)
> Create   1280 rrds      1 c/s (0.35445 sdv)   Update   2560 rrds    4294 
> u/s (0.00614 sdv)
> Create    768 rrds      1 c/s (0.05230 sdv)   Update   3328 rrds    3626 
> u/s (0.00785 sdv)
> 
> 
> RRDtool 1.3:
> 
> Create     10 rrds      1 c/s (0.00771 sdv)   Update     10 rrds   31434 
> u/s (0.00007 sdv)
> Create     10 rrds      1 c/s (0.00421 sdv)   Update     20 rrds   29388 
> u/s (0.00031 sdv)
> Create     20 rrds      1 c/s (0.00937 sdv)   Update     40 rrds   24646 
> u/s (0.00068 sdv)
> Create     40 rrds      3 c/s (0.40489 sdv)   Update     80 rrds   16121 
> u/s (0.00132 sdv)
> Create     80 rrds      5 c/s (0.04052 sdv)   Update    160 rrds    2000 
> u/s (0.00519 sdv)
> Create    160 rrds      2 c/s (0.12109 sdv)   Update    320 rrds      33 
> u/s (0.02963 sdv)
> 
> $ uname -a
> Linux yossarian 2.6.20-16-generic #2 SMP Thu Jun 7 20:19:32 UTC 2007 
> i686 GNU/Linux
> 
> I didn't configure with any special options. Ideas?
> 
> Evan
> 
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