Rik van Riel wrote:
>
> On Tue, 9 Jan 2001, Daniel Phillips wrote:
> > Linus Torvalds wrote:
> > > (This is why I worked so hard at getting the PageDirty semantics right in
> > > the last two months or so - and why I released 2.4.0 when I did. Getting
> > > PageDirty right was the big step to make all of the VM stuff possible in
> > > the first place. Even if it probably looked a bit foolhardy to change the
> > > semantics of "writepage()" quite radically just before 2.4 was released).
> >
> > On the topic of writepage, it's not symmetric with readpage at
> > the moment - it still takes (struct file *). Is this in the
> > cleanup pipeline? It looks like nfs_readpage already ignores
> > the struct file *, but maybe some other net filesystems are
> > still depending on it.
>
> writepage() and readpage() will never be symmetric...
>
> readpage()
> program can't continue until data is there
> reading in larger clusters eats (wastes?) more memory
> done when we think a process needs data
>
> writepage()
> called after the process has written data and moved on
> writing larger clusters has no influence on memory use
> often done to free up memory
>
> Since readpage() needs to tune readahead behaviour, we will
> always want to give it some information (eg. in the file *)
> so it can do the extra things it needs to do.
Which extra information did you have in mind?
--
Daniel
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