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Date: March 05, 1985 23:07
From: KIM::SHEPPERD
To: @sys$mail:everybody.uaf
Has anybody noticed that Kim is kinda S-L-O-W sometimes? This is actually due to a couple of things: one is that that you guys are using Kim to do lots of hard work (this is good, keep it up). The other is that VMS 4 and its associated processes gobble up about 2Mb of memory out of an available total of 4. This is about 1000 pages more than under VMS 3 (once again proves that software grows to fill the available space) and as a consequence, programs running on Kim do a lot more page faulting. What's even worse is that most of these additional page faults are "hard" in that they are resolved by disk accesses. There is (or will be shortly) a document called DOK:PAGES.DOC that describes in some detail how VMS manages its memory. Read it if you're intrested. In the meantime you can take it on blind faith that Kim needs more memory to reduce these page fault rates, which in turn will make it run faster. There are two ways to achieve this goal, one by hardware and one by software. The hardware solution costs about $40k (buy more memory) and there's no chance of gettin that kind of money. The software solution is to reduce the demand on Kim's memory. One can achieve this by restricting access (boo-hiss), kicking off users (blech) or by having the users help VMS manage its memory. Its this last method that I want to try so I've written up a little program to do just that. You guys have to help out by getting into the habit of running this program yourself. I've tried to make it as easy as possible for you to do this by setting up all the VT100 type terminals for "applications keypad" and defining the keypad 0 key to "RUN SLEEP". All you have to do is press the 0 key on the keypad if you expect not to be doing any work at your terminal for anywhere from a few seconds to several hours. To wake up your terminal again, just type any key which can if fact be the first character of your next command. For the blue box development system people, DOWNC automatically chains to SLEEP at program termination. (For all those who have already defined their keypad 0 key to mean something else, sorry about that, your definition wins so you'll have to define some other key sequence to SLEEP. You can require that your password be entered to "wake up" your terminal by running SLEEPWP which is done easily by pressing the PF1 (gold) followed by the 0 key. Please understand that you're not giving up anything in either performance or functionality in doing this, it only improves system performance for everyone by allowing programs to use more memory TEMPORARILY. You get back all the pages you freed up (plus more if you need them) as soon as you "wake up". You may think "Why should I give my pages? I want to keep them all!" Actually, if the system gets real busy, it'll take ALL your pages away from you whether you are sleeping or not. It is NOT possible to hoard pages. But by sleeping, you volunteer your pages for somebody else saving the system the trouble of being sneaky about taking them from you. Also, don't expect Kim to suddenly get 10 times faster. I realistically expect that it will change from S----L----O----W to a mere S---L---O---W, but every little bit helps in this case. As an added bonus, ZAP_THE_USER will leave your process alone if you are running sleep and the process(es) sleeping with password won't get zapped at 23:30. You can use sleep with password in lieu of logging out, which makes logging back in as fast as just typing your password. But please don't sleep with password on public terminals since it will prevent users who don't know your password from using them. You will notice that Sleep says who it's waiting for, so if you inadvertantly lock up, say the VT100 in the DIO room, you will surely be hunted down and set upon by an angry mob of users. Should you find that you've done such a foul deed, SUICIDE from any other terminal will quickly solve the problem. Lucky for us so far, we can correct such breaches of honor by comitting SUICIDE with a few keystrokes at our terminal instead of the more conventional everlasting method requiring the use of a blade.
Mar 05, 1985