[Lustre-devel] Some investigations on MDS creation rate

[Alex Zhuravlev]

Oleg Drokin wrote:
>    I also performed tests on HEAD and it performs significantly worse  
> (5.8k at most). Even with all the same fixes ported from b1_6.
>    The CPU remains the same and I used lock meter to verify that there  
> is no significant lock contention.
>    Looking into the oprofile results, it looks like all code just  
> became slower (judging by more hits in various areas for the same  
> workload).
>    Also some parts of the code are now more heavily loaded (ptlrpc 
> +ldlm in HEAD draws more cpu time, llite portion of the code is 50%  
> more time

notice HEAD takes two ldlm locks for each create, 1.6 takes one.

>    I have no idea why the variability and I do not see anything very  
> obvious that would explain sudden overall performance degradation of  
> HEAD code either yet.

it would  be interesting to gather L1/L2 cache hit/miss with oprofile for
1.6 and HEAD.

thanks, Alex