[Lustre-devel] statahead feature

Alex Zhuravlev Alex.Zhuravlev at Sun.COM
Fri Jul 25 12:50:13 PDT 2008

Andreas Dilger wrote:
> IMHO it would also be useful to start the OST glimpse in the callback as
> soon as the MDT "glimpse" is returned.  Without a change like this we
> are limited to <= 2x speedup for statahead until size-on-MDS is done.
> That is because we are hiding the MDT RPC latency, but still have to wait
> for the parallel OST RPC latency, so:
> speedup = (old time / new time) = (MDT RPC + max(OST RPC)) / max(OST RPC)


thanks, Alex

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