Re: Soft-Updates for Linux ?

From: Rik van Riel (riel@conectiva.com.br)
Date: Sun Oct 01 2000 - 22:07:56 EST


On Mon, 2 Oct 2000, Daniel Phillips wrote:
> Rik van Riel wrote:
> >
> > Local mechanisms simply CANNOT make page replacement work
> > well on a system-wide level.
>
> I think you mean 'local mechanisms alone'. The question is not
> *whether* the subsystems will work together, but *how*. I have
> a nagging feeling we can do a little better than the mechanism
> currently on the table.

That's up to the filesystems ;)

If the VM does a page->mapping->flush() callback and the
filesystem flushes (on average) 20 pages as a result of
such a callback, we'll only have to do the callback for
5% of the pages ...

Also, by speeding up / slowing down bdflush (kflushd) as
appropriate, you can avoid having to do the flush callback
at all most of the time. (for "normal" access patterns
and under "normal" loads)

The ->flush() callback is mostly there for those situations
in which we have a big discrepancy between the filesystem
writeout order and the VM page reclaim order...

regards,

Rik

--
"What you're running that piece of shit Gnome?!?!"
       -- Miguel de Icaza, UKUUG 2000

http://www.conectiva.com/ http://www.surriel.com/

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