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List:       kde-devel
Subject:    Re: About memory allocation failures....
From:       Kuba Ober <kuba () mareimbrium ! org>
Date:       2002-02-05 16:15:24
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On Monday 04 February 2002 06:24 pm, aleXXX wrote:
> On Monday 04 February 2002 18:04, Kuba Ober wrote:
> > That's true, although kde doesn't really work on systems with per-user
> > limits. I'm working periodically on one such a system (freebsd 1gig ram
> > student server with 2 decent pIII processors, top-notch motherboard,
> > top-notch scsi drives, 2gig of swap with disk-file-to-disk-file dd
> > transfer of about 100mb/s) - as soon as two student labs (about 15
> > machines) run kde (just starting the desktop), things get itchy, and then
> > each student has otherwise-reasonable limits (2 minutes process runtime
> > is one of them) - kde is useless on such a system. Nobody can help, and
> > the small
> > memory-watcher utility won't help either. Kde does a good job on a single
> > user workstations without limits in place, or on small servers with less
> > than a few users. I don't know what kind of hardware would one need (and
> > if such beasts exist at all) to run a 100 user kde desktop server (with x
> > terminals attached via ethernet).... :-(
>
> Doesn't the legendary "City of Largo" exactly that ?
> Running a lot (tens to hundreds) clients with one big server ?

I'm just saying that a top-of-the notch mid-sized machine: very good 
motherboard, 2xpiii, 1gig ecc ram, 2gig swap, very-fast scsi-based drives 
(100mbyte/s xfer), up-to-date freebsd os, is not able to cope with more than 
15-20 users trying to play with recent kde desktop at the same time. It works 
fine with fairly high loads of things like irc (it hosts a large irc server), 
pine, compressing/decompressing files, etc. I have no clue what one would 
have to use to have hundreds of users - probably some Compaq 16-processor 
beast with *much* more than 1gig of ram :-((.

Another thing is that kde apps don't behave nicely when process rss limit is 
16mb, at least not on that freebsd system. Effect is that applications 
"vanish" when you're using them. Now, for a multi-user system with 1gig of 
ram, with 50 users typically logged in (text sessions) during peak hours, 
there's no point in having per-user rss limit higher than 16mb - it could 
have as well been nonexistent.

So kde is not there yet for multi-user systems, or I'm severely 
musunderstanding something - thus replies are welcome.

Most of it can be attributed to current gcc in cooperation with Qt, I 
believe, since C++ code and data sharing doesn't work miracles yet, I'm 
afraid. I presume that a simple thing as mmap-ing all resource files (icons, 
disk-based html help files, etc.) would help things a lot, but that's not 
all. Or maybe it's already done that way??? A lot of memory in kde apps 
running on multiuser servers is wasted to store same things over and over.... 
I did a full memory dump once on big system running many kde user sessions, 
and whooping 7% of pages (and page-sized memory chunks, as all offsets were 
tested) had exact duplicates, and about 20% had duplicates with small 
differences only - loader fixups :-(( These are resident, live, physical 
in-ram pages, I'm not talking about swap. All of these pages were owned by 
kde processes (applications).

Cheers,
Kuba
 
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