Subject: Re: nfs unhappiness with memory pressure
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Andrew Morton <akpm@osdl.org>
Cc: theonetruekenny@yahoo.com, linux-kernel@vger.kernel.org
In-Reply-To: <20051206143641.3feadaea.akpm@osdl.org>
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	 <20051206143641.3feadaea.akpm@osdl.org>
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Date: Mon, 05 Dec 2005 23:40:26 -0500
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On Tue, 2005-12-06 at 14:36 +1100, Andrew Morton wrote:
> Trond Myklebust <trond.myklebust@fys.uio.no> wrote:
> >
> > Argh... Not sure entirely how to deal with that... We definitely don't
> >  want the thing futzing around inside throttle_vm_writeout(), 'cos
> >  writeout isn't going to happen while the socket blocks.
> > 
> 
> As far as the core VM is concerned, these pages are really "dirty", only it
> happens to be a different flavour of dirtiness.  So perhaps we should
> continue to mark these pages as dirty and let NFS internally take care
> of which end of the wire they're dirty at.
> 
> Presumably calling writepage() a second time won't be very useful.  Or will
> it?  Perhaps when NFS sees writepage against a PageDirty && PageUnstable
> page it can recognise that as a hint to kick off a server-side write.

Calling writepages() would actually be better. That will do the right
thing, and trigger a commit if there are unstable writes.

Cheers,
  Trond

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