Re: on load control / process swapping

[Alfred Perlstein <bright@rush.net>]

* Matt Dillon <dillon@earth.backplane.com> [010516 14:01] wrote:
> 
>     I think someone tried to implement O_DIRECT a while back, but it
>     was fairly complex to try to do away with caching entirely.
> 
>     I think our best bet to 'start' an implementation of O_DIRECT is
>     to support the flag in open() and fcntl(), and have it simply
>     modify the sequential detection heuristic to throw away pages
>     and buffers rather then simply depressing their priority.

yes, as i said:

> :A simple solution would involve passing along flags such that if
> :the IO occurs to a non-previously-cached page the buf/page is
> :immediately placed on the free list upon completion.  That way the
> :next IO can pull the now useless bufferspace from the freelist.
> :
> :Basically you add another buffer queue for "throw away" data that
> :exists as a "barely cached" queue.  This way your normal data
> :doesn't compete on the LRU with non-cached data.
> 
>     Eventually we can implement the direct-I/O piece of the equation.
> 
>     I could do this first part in an hour, I think.  When I get home....

Thank you.

-Alfred
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux.eu.org/Linux-MM/