Re: nfs unhappiness with memory pressure

From: Trond Myklebust
Date: Mon Dec 05 2005 - 23:40:09 EST


On Tue, 2005-12-06 at 14:36 +1100, Andrew Morton wrote:
> Trond Myklebust <trond.myklebust@xxxxxxxxxx> 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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