Ubuntu's performance : how to speed up ?

[Erik Bågfors]

On Tue, 15 Feb 2005 10:17:05 +0100, Vincent Trouilliez
<vincent.trouilliez at modulonet.fr> wrote:
> I was wondering how I could speed up Ubuntu.
> 
> A friend who has a dual CPU motherboard told me all the benefits of
> using two CPUs with Linux. Basically, Linux being such a huge
> collection/stack/pile of daemons, services, processes etc, especially
> Gnome, executing two of them at the same time really speed things up !
> So, I am sold, my next board will be a dual CPU one.

Probably will not give you as much of a performace boost as you think.

In a normal PC used for normal users, be it windows, linux or macos,
it's usually NOT CPU that's the bottleneck. It's usually memory-size,
harddisk-speed and general bandwidth within the computer.

I really think you'll get alot more computer for the money by
adressing these issues.

For computing intense machines it's a really good thing to have a SMP system.

I've been working alot in the HPC (High Performance Computing)
industri (for research mostly) and have been using many many SMP
computers and for really computing intense application. Such as FFT or
weather calculations it's really a big performance booster.

> Now, seeing as hard disk performance seems to greatly affect Gnome's
> performance, and seeing that my 40GB drive is a few years old already, I
> am wondering how much faster modern drives are. Drives being cheap, that
> could be a simple way to speed up Ubuntu a bit, until I can afford an
> expensive motherboard.
> 
> I tested my drive transfer rate with hdparm : "sudo hdparm -t /dev/hda"
> I ran it 3 times, and it's about between 15 and 20MB per second.
> 
> Could someone with a super modern (IDE or SCSI) hard drive, run this
> command so I can get a feel for how much better modern drives are, ie,
> is it worth buying one ? Thanks. :-)

Seeing that you write below that you only have 512BM or RAM. Double
that instead.  Will give you much more speed.

After that, sure.. update the drive to something better.  hdparm may
not be the best performace monitor but my laptop gets about the same
numbers as you do. Get some 10krpm disks instead and you should see a
performance boost

> Last thing, seeing as RAM is cheap, and modern boards can carry huge
> amounts of RAM, and seeing as my  /usr folder weigth "only" 2.0GB of
> data, would it be possible to put say 4GB of RAM on the board, use 2GB
> as norma system RAM, and the other 2GB of RAM to pre-load the
> entire /usr forlder at boot ?
> Is there a mechanism in Linux (Kernel ? or higher-level stuff ?) that
> would allow preloading some data into RAM at boot ?

Much better to let the kernel use this extra memory for file caching.
Which it does by default. That way you only need to read the disk the
first time you run an app from /usr and the next time it's only
loading it from file cache (unless that space has been used for
something else).  This way your computer will not have to load lot's
of junk into the RAM that you never use.
 
> I have "only" 512B of RAM right now, but it could be enough to
> experiment anyway. Since Ubuntu runs fine with 256MB of RAM, I could sue
> the other 256MB to load a small part of /usr, say OpenOffice.org for
> example, as it's so slow to load from the disk.

Use the OOo applet. It preloads OOo for you so that it's already
loaded into memory when you want to run it.

Regards,
Erik