[clug] Ubuntu at the low end

[Jason Stokes]

I've been playing with Ubuntu 8.04 for the past couple of weeks on a
very old PC -- a PII-400-MMX with 256 MB of PC100 RAM, and a TNT II
video card.  I had previously installed 7.04 on it last year (the old
"stick it on an old PC and try it out" school of Linux adoption), took a
look at it, and promptly forgotten about it.  Installing 8.04 reminded
me /why/ I had forgotten about it: because Ubuntu, out of the box, is
slow as a dog on it, at least as far as running Gnome on the desktop
goes.  Scrolling is slow.  Page rendering is appalling, and
tab-switching is painful. Load times are shocking.

The scandal is that with just a little optimization, I've found Ubuntu's
desktop performance on this machine can be vastly improved.  It's still
a little sluggish on some things, and load times are still an issue with
some apps, but it's definitely useable.  In fact, the effects are so
noticible that it suggests that it is possible to make dramatic software
optimizations in the Gnome/Xorg code base, if only the developer will
existed.   More on this below.

Some subjective impressions on what performance tweaks worked:

* 256 MB of ram just isn't enough for Gnome, no matter how much you
tweak.  The system would swap constantly.  I added an extra 256 MB
stick, I had lying around and the system is now very comfortable. I
would split the difference, and say that the minimum RAM you need is 384
MB.
* Choice of gtk theme has a /big/ influence on responsiveness.  The
default Ubuntu theme (human) is extremely slow.  The fastest theme I've
tried is ThinIce, which turns Gnome apps from sluggish to actually quite
responsive.  Surprisingly to me, changing the theme to thinice yielded
the biggest singular performance improvement.
* Disregarding the philosophical issues, if you care about performance,
definitely try a binary-only xorg module.   I'm using the "legacy
nvidia" driver and it's responsible for a noticible improvement in
drawing speed.
*  Slow load time is hard to fix.  Hdparm on /dev/sda doesn't yield
anything very helpful:

/dev/sda:
 IO_support    =  0 (default) 
16-bit)
 HDIO_GET_UNMASKINTR failed: Inappropriate ioctl for device
 HDIO_GET_DMA failed: Inappropriate ioctl for device
 HDIO_GET_KEEPSETTINGS failed: Inappropriate ioctl for device
 readonly      =  0 (off)
 readahead     = 256 (on)
 geometry      = 1247/255/63, sectors = 20044080, start = 0

I'm pretty sure that the kernel is actually using the optimal transfer
settings for the drive, given that the BIOS seems pretty solid.  I think
it's just an old, slow hard drive and it's being called upon to load
some pretty bloated applications.

Some guides recommend installing "preload", a kernel daemon that
monitors frequently used applications and prefetches them into the
kernel disk cache.  Based on my experience, preload definitely seems to
work, but the performance improvements are modest and incremental rather
than dramatic.
* You really learn who your friends are running a PC this slow.  Firefox
3 release is noticeably faster than the beta.  Anjuta using the
GtkSourceView editing plugin is really snappish, whereas Anjuta using
the Scintilla editing plugin is unuseable.  And of course even users on
much more modern PCs complain about how bloated an app like Nautilus is.

In other words, the quality of the coding in the application /matters/.
The difference between efficient and inefficient coding is extremely
noticible on hardware this low end.  Based on my experience, I would say
that if the Gnome team made a concerted effort to improve the efficiency
of their code-base across the board, performance on the low-end would
improve dramatically.  This would have flow-on effects even for those
not using 10 year old PCs.  Indeed, I believe that one way to get
movement on the Gnome performance issues would be to force the Gnome
developers to use 400 Mhz PCs for their daily work.  I would bet that
they would quicky find a way to optimize their way around the
performance bottlenecks.

Performance optimization is particularly important because I believe the
low-end is an important niche for Linux.  There's the "old PC" install
base.  There's developing countries, for whom any PC is a luxury.
There's the growing "small cheap machines" market, which Ubuntu
currently struggles on (for example, the gentleman at the last CLUG
whose Ubuntu install on his Asus PC took several minutes to boot up.)

There's an organization called "charity computers which has branches in
Canberra and Brisbane: http://www.charitycomputers.com.  Charity
Computers provides old PCs cheaply to the unemployed, hard-off etc.
They pre-load versions of Windows on these PCs, and give them out to the
unemployed, hard-off, etc -- in fact, by admission completely illegally,
since the cost of the license fees from Microsoft would eclipse the cost
of the PC.  I don't know how they've dealt with the mandatory
registration requirements of XP and Vista.  

I've often wanted to suggest to them that they switch to Linux for those
PCs, but as it is the performance issues are real enough.  I want people
to be impressed when they put Linux on an old PC, not disappointed by
slow performance.  There are also very real useability issues I've
noticed in Ubuntu, but that's an issue for another day.

Jason