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SubjectRe: mmap()/VM problem in 2.4.0

On Fri, 19 Jan 2001, Rik van Riel wrote:

> On Thu, 18 Jan 2001, Marcelo Tosatti wrote:
> > On Thu, 18 Jan 2001, Rik van Riel wrote:
> > > On Fri, 12 Jan 2001, Vlad Bolkhovitine wrote:
> > >
> > > > You can see, mmap() read performance dropped significantly as
> > > > well as read() one raised. Plus, "interactivity" of 2.4.0 system
> > > > was much worse during mmap'ed test, than using read()
> > > > (everything was quite smooth here). 2.4.0-test7 was badly
> > > > interactive in both cases.
> > >
> > > Could have to do with page_launder() ... I'm working on
> > > streaming mmap() performance here and have been working
> > > on this for a week now (amongst other things).
> >
> > Also remember that drop_behind() is not working for mmap(), yet...
>
> filemap_sync(..., MS_INVALIDATE) needs a 2-line change to have
> drop-behind. I have this running (more or less) on my laptop here.

The filemap_sync() modifications on your patch makes msync
(MS_SYNC|MS_INVALIDATE) not work correctly anymore. filemap_sync() must
set the page dirty for all valid pte's in the requested area if MS_SYNC is
set.
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