[Lustre-discuss] Lustre MPI-IO performance on CNL

Weikuan Yu weikuan.yu at gmail.com
Wed Mar 5 10:58:11 PST 2008


> What is the stripe_size of this test? 4M? If it is 4M, then 
> transfer_size is a little
> bigger(64M). And we have seen this situation before, finally it seems 
> because client hold
> too much lock in each write(because of lustre down-forward extent lock 
> policy) which might
> block other client writing, so impact the parallel of the whole system. 
> Maybe you could try
> decrease transfer size to stripe_size. Or increase stripe_size to 64M 
> and see how is it?

Yes, the situation between shared file and separated files has been seen 
before. But I have never seen an explanation regarding CNL. BTW, this 
performance difference between shared/separated stays the same, 
regardless what transfer size is.

Anybody wants to post a reason regarding direct I/O too?

--Weikuan




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