RE: Speeding up swap

David Schwartz (davids@webmaster.com)
Sun, 24 Oct 1999 09:29:44 -0700


> I am looking for a mechanism that enables a user process to
> advise the kernel on a per-fd basis not to keep more than say
> two pages of a certain file any buffer cache based on the
> promise that the user process will read that file only in a
> sequentially-forward or even non-seeking manner. I exspect
> performance improvements from such a mechanism because I
> observed that unrelated user processes get paged out when a very
> large file is passed thru a streaming application.

If you allow it to be used by non-privileged processes, you create the
potential for an untrusted process to cause ridiculous amounts of physical
I/O. Although one could argue that an untrusted process can currently cause
as much damage by repeatedly reading sequentially through a file much larger
than physical memory.

DS

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