[Info-vax] Raxco VMS Tuning Seminar Notes

[Neil Rieck]

On Nov 1, 12:10 pm, jls <notva... at yahoo.com> wrote:

>
> Again with the "always".  The drawbacks with this memory management
> technique are:
>         1. it uses CPU to constantly manage memory, thus taking
> available CPU from users  This is a trade-off that is not adequately
> understood by many people.
>         2. it only takes memory from ACTIVE users, not idle users.
> This forces the active users to pagefault much more to get work done.
>

How could the SWAPPER not trim idle users? They would be faulting at a
rate of less than PFRATL (if not zero). As I under stand this, you
would want to trim the working set to a smaller size then swap out
that smaller set. Not all trimmed pages would ever be faulted back in
(based upon the theory that you run 10% of the code 90% of the time)

You are correct that some CPU resources are used to do this, but this
could be reduced by increasing AWSTIME to 1, or more, multiples of
QUANTUM. Anyway, having any program scan the system on a periodic
basis (watchdog, hitman, etc.) can take its toll.

NSR