Re: [patch] vmfixes-2.4.0-test9-B2 - fixing deadlocks

Rik van Riel
2000-09-29T14:39:18Z

On Thu, 28 Sep 2000, Andrea Arcangeli wrote:
> On Thu, Sep 28, 2000 at 08:16:32AM -0300, Rik van Riel wrote:
> > Andrea, I have the strong impression that your idea of
> > memory balancing is based on the idea that the OS should
> > out-smart the application instead of looking at the usage
> > pattern of the pages in memory.
>
> Not sure what you mean with out-smart.
>
> My only point is that the OS actually can only swapout such shm.
> If that SHM is not supposed to be swapped out and if the OS I/O
> cache have more aging then the shm cache, then the OS should
> tell the DBMS that it's time to shrink some shm page by freeing
> it.

OK, good to see that we agree on the fact that we
should age and swapout all pages equally agressively.

> > of the pages in question, instead of making presumptions
> > based on what kind of cache the page is in.
>
> For the mapped pages we never make presumptions. We always check
> the accessed bit and that's the most reliable info to know if
> the page is been accessed recently (set from the cpu accesse
> through the pte not only during page faults or cache hits).
> With the current design pages mapped multiple times will be
> overaged a bit but this can't be fixed until we make a page->pte
> reverse lookup...

Indeed.

regards,

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

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