Re: VM Requirement Document - v0.0

[Jeffrey W. Baker]

On Wed, 27 Jun 2001, Stefan Hoffmeister wrote:

> : On Tue, 26 Jun 2001 18:42:56 -0300 (BRST), Rik van Riel wrote:
>
> >On Tue, 26 Jun 2001, John Stoffel wrote:
> >
> >> Or that we're doing big sequential reads of file(s) which are
> >> larger than memory, in which case expanding the cache size buys
> >> us nothing, and can actually hurt us alot.
> >
> >That's a big "OR".  I think we should have an algorithm to
> >see which of these two is the case, otherwise we're just
> >making the wrong decision half of the time.
>
> Windows NT/2000 has flags that can be for each CreateFile operation
> ("open" in Unix terms), for instance
>
>   FILE_ATTRIBUTE_TEMPORARY
>
>   FILE_FLAG_WRITE_THROUGH
>   FILE_FLAG_NO_BUFFERING
>   FILE_FLAG_RANDOM_ACCESS
>   FILE_FLAG_SEQUENTIAL_SCAN
>
> If Linux does not have mechanism that would allow the signalling of
> specific use case, it might be helpful to implement such a hinting system?

These flags would be really handy.  We already have the raw device for
sequential reading of e.g. CDROM and DVD devices.

-jwb