Re: journaling & VM (was: Re: reiserfs being part of the kernel: it'snot just the code)

Jeff V. Merkey
2000-06-07T17:10:28Z

Stephen,

When will the journalling subsystem you are working on be available, and
where can I get it to start integration work. It sounds like you will
be "bundling" associated LRU meta-data blocks in the buffer cache for
journal commits? What Alan described to me sounds fairly decent. I am
wondering when you will have this posted so the rest of us can
instrument your journalling code into our FS's.

Please advise.

:-)

Jeff

"Stephen C. Tweedie" wrote:
>
> Hi,
>
> On Wed, Jun 07, 2000 at 05:20:41PM +0200, Quintela Carreira Juan J. wrote:
> >
> > stephen> It doesn't matter. *If* the filesystem knows better than the
> > stephen> page cleaner what progress can be made, then let the filesystem
> > stephen> make progress where it can. There are likely to be transaction
> > stephen> dependencies which mean we have to clean some pages in a specific
> > stephen> order. As soon as the page cleaner starts exerting back pressure
> > stephen> on the filesystem, the filesystem needs to start clearing stuff,
> > stephen> and if that means we have to start cleaning things that shrink_
> > stephen> mmap didn't expect us to, then that's fine.
> >
> > I don't like that, if you put some page in the LRU cache, that means
> > that you think that _this_ page is freeable.
>
> Remember that Rik is talking about multiple LRUs. Pages can only
> be on the inactive LRU if they are clean and unpinned, yes, but we
> still need a way of tracking pages which are in a more difficult
> state.
>
> > If you need pages in the LRU cache only for getting notifications,
> > then change the system to send notifications each time that we are
> > short of memory.
>
> It's a matter of pressure. The filesystem with most pages in the LRU
> cache, or with the oldest pages there, should stand the greatest chance
> of being the first one told to clean up its act.
>
> Cheers,
> Stephen
>
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