Re: VM Requirement Document - v0.0

Dan Maas (dmaas@dcine.com)
Tue, 26 Jun 2001 20:43:33 -0400


> 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
>

There is a BSD-originated convention for this - madvise().

If you look in the Linux VM code there is a bit of explicit code for
different madvise access patterns, but I'm not sure if it's 100% supported.

Drop-behind would be really, really nice to have for my multimedia
applications. I routinely deal with very large video files (several times
larger than my RAM). When I sequentially read though such files a bit at a
time, I do NOT want the old pages sitting there in RAM while all of my other
running programs are rudely paged out...

(hrm, maybe I could hack up my own manual read-ahead/drop-behind with mmap()
and memory locking...)

Regards,
Dan

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/