From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alex Zhuravlev <Alex.Zhuravlev@Sun.COM>
Date: Fri, 25 Jul 2008 23:50:13 +0400
Subject: [Lustre-devel] statahead feature
In-Reply-To: <20080725194109.GV5346@webber.adilger.int>
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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)

definitely

thanks, Alex