On Thu, 28 Sep 2000, Andrea Arcangeli wrote:

On Thu, Sep 28, 2000 at 08:16:32AM -0300, Rik van Riel wrote:

quoted

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.

quoted

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

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

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