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

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Date:	Wed, 14 May 2008 12:08:01 +0400
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: POHMELFS high performance network filesystem. Transactions, failover, performance.

On Wed, May 14, 2008 at 11:40:28AM +0400, Evgeniy Polyakov (johnpol@....mipt.ru) 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.

-- 
	Evgeniy Polyakov
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