Re: mmap over nfs leads to excessive system load

From: Trond Myklebust
Date: Wed Nov 16 2005 - 19:28:05 EST


On Wed, 2005-11-16 at 16:25 -0800, Andrew Morton wrote:
> Trond Myklebust <trond.myklebust@xxxxxxxxxx> wrote:
> >
> > The accompanying NFS patch makes use of this in order to figure out when
> > to flush the data correctly.
>
> OK. So with that patch, nfs_writepages() may still leave I/O pending,
> uninitiated, yes?
>
> I don't understand why NFS hasn't been BUGging as it stands at present. It
> has several end_page_writeback() calls but no set_page_writeback()s.
> end_page_writeback() or rotate_reclaimable_page() will go BUG if the page
> wasn't PageWriteback().

It does have SetPageWriteback() calls in the asynchronous writeback
path. As you can see from the patch I just sent, I only needed to
replace them with set_page_writebacks().

Cheers,
Trond

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