[Info-vax] Running Alpha VMS under the ES40 emulator

[johnwallace4 at yahoo.co.uk]

On Friday, 11 October 2013 15:58:01 UTC+1, George Cornelius  wrote:
> johnwallace4 at yahoo.co.uk wrote:
> 
> 
> 
> > Don't know whether readers are all aware, but in AMD64 mode, you gain not just a wider virtual address, which may or may not be a winner, but you also gain twice (roughly) the number of CPU registers, and a few other new featurettes. Twice as many registers is frequently useful, as any PDP11 assembler programmer (or compiler author) will tell you.
> 
> > 
> 
> > So a program that doesn't need a 64bit VA *may* get a performance gain simply because it has more registers to play with. On the other hand, in 64bit VA mode, pointers etc take up twice as much cache space. It's not always a guaranteed win to switch to 64bit mode, though it frequently is.
> 
> > 
> 
> > Apologies if I'm repeating myself here.
> 
> 
> 
> So, for arrays of pointers, or code with lots of 64 bit
> 
> memory references, it can be costly.  But a 64 bit processor
> 
> may have more cache; and ability to address beyond 4 MB can
> 
> be a huge gain, and more so as time goes on, with more and
> 
> more applications just don't cope well with a memory
> 
> constraint of that sort.
> 
> 
> 
> I'm finding that what it takes to almost completely freeze
> 
> up my 512 MB / 32 bit Linux system is to leave Mozilla up
> 
> overnight with multiple tabs open.  It pagefaults for what
> 
> seems to be a full 15 minutes at that point, and may still
> 
> be nearly unusable when it all unfreezes [OK, using an
> 
> external Seagate USB3 drive on a USB2 port for paging -
> 
> spinning at an unspecified RPM - but you get the picture].
> 
> 
> 
> George


You're using Firefox (or similar) in only 512MB?

Firefox implies a relatively modern GUI-centric OS, right?

512MB RAM (for both code and data) is not the typical design centre
for a modern GUI-centric OS. It might barely be OK for the non-GUI variant
of the same OS, but if you want a GUI, maybe you need to look at your
choice of GUI and what you're using in it.

There are a variety of relatively lightweight desktop environments
around with different window managers and apps, some of which are getting
more exposure courtesy of lightweight Linux systems such as Raspberry
Pi. Lightweight here means less heavyweight than KDE or Gnome etc.
Potential candidates might included LXDE, Fluxbox, etc. If you haven't
already done so, you might want to have a look around.

Firefox is known to be a particular memory hog in some versions (maybe
most), probably it never discards anything once you've read it. Maybe
that's the price you pay for not using Lynx any more?

We shouldn't really expect "modern" software to run well in
resource-limited environments.


1980s: How do you tune a VAX?
Add more memory.

2000s: How do you tune a 512MB Linux system?
Add more memory.
(Or at least choose a lighterweight desktop environment).


Apologies if you already knew all this, best of luck anyway.