Re: POHMELFS high performance network filesystem. Transactions,failover, performance.

[Sage Weil]

> On Wed, May 14, 2008 at 11:40:28AM +0400, Evgeniy Polyakov (johnpol@xxxxxxxxxxx) wrote:
> > > If any thread takes more than one kmap() at a time, it is deadlockable.
> > > Because there is a finite pool of kmaps.  Everyone can end up holding
> > > one or more kmaps, then waiting for someone else to release one.
> > 
> > It never takes the whole LAST_PKMAP maps. So the same can be applied to
> > any user who kmaps at least one page - while user waits for free slot,
> > it can be reused by someone else and so on.
> 
> Actually CIFS uses the same logic: maps multiple pages in wrteback path
> and release them after received reply.

Yes.  Only a pagevec at a time, though... apparently 14 is a small enough 
number not to bite too many people in practice?

sage
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