[Linux-cluster] Slowness above 500 RRDs

[David Teigland]

On Tue, Jun 12, 2007 at 05:43:24PM +0200, Ferenc Wagner wrote:
> Let's see.  Mounting on one more node (and switching on the third):
> 
> # cman_tool services
> type             level name     id       state       
> fence            0     default  00010001 none        
> [1 2 3]
> dlm              1     clvmd    00020001 none        
> [1 2 3]
> dlm              1     test     000a0001 none        
> [1 2]
> gfs              2     test     00090001 none        
> [1 2]
> 
> $ <commands to run the test>
> filecount=500
>   iteration=0 elapsed time=5.030971 s
>   iteration=1 elapsed time=0.657682 s
>   iteration=2 elapsed time=0.798228 s
>   iteration=3 elapsed time=0.65742 s
>   iteration=4 elapsed time=0.776301 s
> total elapsed time=7.920602 s
> 
> Somewhat slower, yes.  But still pretty fast.
> 
> Mounting on the third node:
> 
> # cman_tool services
> type             level name     id       state       
> fence            0     default  00010001 none        
> [1 2 3]
> dlm              1     clvmd    00020001 none        
> [1 2 3]
> dlm              1     test     000a0001 none        
> [1 2 3]
> gfs              2     test     00090001 none        
> [1 2 3]
> 
> $ <commands to run the test>
> filecount=500
>   iteration=0 elapsed time=0.822107 s
>   iteration=1 elapsed time=0.656789 s
>   iteration=2 elapsed time=0.657798 s
>   iteration=3 elapsed time=0.881496 s
>   iteration=4 elapsed time=0.659481 s
> total elapsed time=3.677671 s
> 
> It's much the same...

OK, that's interesting.  I was led to believe from some of my old testing
that plocks wouldn't be that fast, but maybe that was a mistaken
conclusion.  There's no reason not to use plocks with -l0 if you're
getting good results.

Dave