Messages in this thread | | | Subject | Re: nfs unhappiness with memory pressure | From | Trond Myklebust <> | Date | Mon, 05 Dec 2005 16:23:08 -0500 |
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On Mon, 2005-12-05 at 16:18 -0500, Trond Myklebust wrote: > On Tue, 2005-12-06 at 07:52 +1100, Nick Piggin wrote: > > > The VM doesn't expect to have to rely on pdflush to write out pages > > for it. ->writepage should be enough. Adding wakeup_pdflush here > > actually could do the wrong thing for non-NFS filesystems if it > > starts more writeback. > > nr_unstable is not going to be set for non-NFS filesystems. 'unstable' > is a caching state in which pages have been written out to the NFS > server, but the server has not yet flushed the data to disk.
...and most important of all: 'unstable' does _not_ mean that I/O is active on those pages (unlike the apparent assumption in vm_throttle_write. That is why the choice is either to kick pdflush there, or to remove nr_unstable from the accounting in that loop.
Cheers, Trond
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