[Linux-cluster] Slowness above 500 RRDs

[Ferenc Wagner]

Ferenc Wagner <wferi at niif.hu> writes:

> So I've got the impression that flock is slower than fcntl locking.
> The difference probably erodes with greater number of files, both
> being equally slow.  I must be missing something, it's just the
> opposite of what you suggest.

For bigger file lists flock seems indeed faster, although not that
much.  I'd like to see the 500-file fcntl behaviour in the 10000-file
regime.  Is that possible with proper tuning of the DLM #defines for
example?  I'll make some random changes, but would appreciate some
guidance.

Regards,
Feri.

FLOCK:

filecount=500
  iteration=0 elapsed time=10.326359 s
  iteration=1 elapsed time=10.470205 s
  iteration=2 elapsed time=10.302251 s
  iteration=3 elapsed time=10.302252 s
  iteration=4 elapsed time=10.562203 s
total elapsed time=51.96327 s
filecount=1000
  iteration=0 elapsed time=21.540327 s
  iteration=1 elapsed time=21.522852 s
  iteration=2 elapsed time=21.860283 s
  iteration=3 elapsed time=21.196407 s
  iteration=4 elapsed time=21.420367 s
total elapsed time=107.540236 s
filecount=2000
  iteration=0 elapsed time=46.920414 s
  iteration=1 elapsed time=42.492109 s
  iteration=2 elapsed time=42.864716 s
  iteration=3 elapsed time=43.092679 s
  iteration=4 elapsed time=43.556623 s
total elapsed time=218.926541 s
filecount=5000
  iteration=0 elapsed time=115.27529 s
  iteration=1 elapsed time=102.525867 s
  iteration=2 elapsed time=102.666411 s
  iteration=3 elapsed time=104.190295 s
  iteration=4 elapsed time=105.114153 s
total elapsed time=529.772016 s

FCNTL:

filecount=500
  iteration=0 elapsed time=9.634164 s
  iteration=1 elapsed time=0.203278 s
  iteration=2 elapsed time=0.204565 s
  iteration=3 elapsed time=0.203895 s
  iteration=4 elapsed time=0.203649 s
total elapsed time=10.449551 s
filecount=1000
  iteration=0 elapsed time=16.111548 s
  iteration=1 elapsed time=27.165518 s
  iteration=2 elapsed time=25.927519 s
  iteration=3 elapsed time=22.904105 s
  iteration=4 elapsed time=23.176309 s
total elapsed time=115.284999 s
filecount=2000
  iteration=0 elapsed time=46.482252 s
  iteration=1 elapsed time=50.130122 s
  iteration=2 elapsed time=45.76822 s
  iteration=3 elapsed time=52.462871 s
  iteration=4 elapsed time=56.386634 s
total elapsed time=251.230099 s
filecount=5000
  iteration=0 elapsed time=125.121509 s
  iteration=1 elapsed time=131.344402 s
  iteration=2 elapsed time=120.272978 s
  iteration=3 elapsed time=126.29043 s
  iteration=4 elapsed time=131.561647 s
total elapsed time=634.590966 s