Re: RFC: mincore: add a bit to indicate a page is dirty.

[Andrew Morton]

On Mon, 11 Feb 2013 11:27:01 -0500
Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> > Is PG_dirty the right choice?  Is that right for huge pages?  Should I
> > assume is_migration_entry(entry) means it's not dirty, or is there some
> > other check here?
> 
> If your only consequence of finding dirty pages is to sync, would you
> be better off using fsync/fdatasync maybe?

Yes, if the data is all on disk then an fsync() will be a no-op.  IOW,

	if (I need to fsync)
		fsync();

is equivalent to

	fsync();


Methinks we need to understand the requirement better.


Also, having to mmap the file to be able to query pagecache state is a
hack.  Whatever happened to the fincore() patch?

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