[Gllug] Writing my own system call

Ian Baillie ian.baillie at westminster.org.uk
Fri Jun 17 18:01:44 UTC 2011

Hi Adrian,

On 17 Jun 2011, at 17:43, Adrian McMenamin <adrian at mcmen.demon.co.uk<mailto:adrian at mcmen.demon.co.uk>> wrote:

On Fri, June 17, 2011 5:35 pm, John Hearns wrote:
On 17 June 2011 17:22, Adrian McMenamin <adrian at mcmen.demon.co.uk<mailto:adrian at mcmen.demon.co.uk>> wrote:
He also said "I am researching/confirming phases of memory locality in
the kernel."

It is an MSc project.

By hacking stuff in user space I can see where the virtual (user space)
memory is coming from, but I want to examine what is going on with
physical addresses too.

Essentially operating system/VMM theory is based on the idea that in a
given (short) time delta allocations will show locality. But at a bigger
range of time that locality may move - perhaps gradually, though more
likely (at least this is the theory/past experimental conclusion) in
rather clearer phases.

Adrian, thankyou for the reply. That's very interesting.

In response to the person who got out of bed on the wrong side this
I happen to work in high performance computing. Arranging processes to
run on particular CPUs
and locality of memory to the job is important.

Actually, I am examining it in terms of "low performance comouting" - ie
thrashing. Wondering if a more aggressive reaping of pages - based on the
sort of working set approach used in VMS (and then in Windows NT) might
have benefits.

It's an MSc rather than a PhD so I cannot claim exactly to be about to
push the boundaries of human knowledge, but as you say its interesting.

Your MSc sounds interesting, do you mind sharing which Uni it is with please. I was going to do an MSc in Computer Science @ Birbeck, which I'm still considering.



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