The state of 64-bit Desktop Linux

[Marc Lanctot]

D. Hugh Redelmeier wrote:
> 
> There is something odd about the slowdown you report.
> 
> Do you know why you feel that it is slowing down?

The GUI becomes unresponsive.. ever app lags, almost as if I was out of 
primary memory and everything is swapping in and out, but top reveals 
nothing unusual (tons of free primary memory). I have 3 GB of memory and 
the most I ever use at one time, after days of leaving everything up, is 
around 1-1.5 GB.

> - Is the bottleneck CPU cycles, disk activity, network bandwidth, or
>   something else?  We have been inferring that you think CPU cycle are
>   the issue.

Definitely not network bandwidth. I doubt disk activity unless there's 
something going on that I don't know about, or Ubuntu is doing something 
wonky. I have reason to believe it's some interaction with the video 
card/driver because sometimes when I restart X it lessens the problem 
for about 20 minutes. Sometimes it doesn't help at all. I'm using NVidia 
proprietary drivers; at first I used the ones packaged with Ubuntu, now 
I mostly just download them from the NVidia site and build them. I have 
a GeForce 8600 GT.

> - if it is CPU cycles, where are they going?  The P4D is pretty fast.
>   In fact, CPUs are not getting much faster in recent years.  Just
>   more cores.  I don't find good machines from four years ago to be
>   slow.
> 
>   + is there heat-throttling going on?  The P4D is quite capable of
>     slowing down when it gets hot.

How can I tell?

>   + is some useless process eating CPU resources?  top(1) might help you
>     discover this.  You can run a graphical system monitor program to
>     show you another dimension of this.  FWIW, I've had Firefox
>     quietly go into 100% CPU-eating mode.  X too.  Flash! might be
>     another villain (I don't have it).

top doesn't reveal a process going wild. But if there is something more 
useful than top it would be good to know.

>   + is some kernel activity eating CPU.  Most tools don't help you
>     figure that out.  I've seen that happen too.

Any tools that do?

>   + are you on Jolt and expecting the CPU to get faster as you do? :-)

I've actually gradually cut my caffeine intake to half of what it was 
last year so if anything I should notice the opposite effect :)

> I recently had an interesting experience.  My hard drive was dying.
> It would cause system slowdowns (I think) because of retrying.  No
> symptoms but speed.  SMART scanning found some problems.  Touch wood,
> the system seems much better with a new drive.

Is SMART an acronym for some program or used for emphasis? I wonder if 
it is disk activity. What did you use to find this?

> | I think it may be because I put a higher-end NVidia card that required a 50W
> | power supply which my casing was not designed for. I did my research on the
> | fans and got the best ones people recommended.. but still it was hot and still
> | it ended up being noisy. It could have just been that the power supply + video
> | card generated too much heat.
> 
> That might be the case (pun intended).
> 
> 50W?  Do you mean 50W extra?  500W?

Sorry, typo, 500W. I was told I needed it for this card, and I think it 
said that on the back of the card's box as well.

> I like HP desktops so far.  Lennart has higher/different standards.
> My HPs have been quite quiet.  But then I've never bought a P4
> (Athlons seemed always like a better choice).

I don't like this thing at all. It's always had problems .. 
repartitioning Windows was a pain and for some reason (BIOS problem?), 
drives are detected in different orders each time I boot in Linux. One 
time I'll boot and my Western Digital will be /dev/sda while my Seagate 
gets /dev/sdb. Next time I'll boot they'll be reversed.

Well I would consider selling it to you at a decent price if you're 
interested :)

> P4s do 64-bit really badly.  I think many 64-bit operations have to go
> through the ALU twice.  It was a tack on.  Athlon 64 and Core 2 are
> quite good at 64-bit operation.
> 
> 64-bit isn't as much of a win as one would expect.  Code density goes
> down so there is higher cache pressure.  I've run x86-64 on my desktop
> for three or four years but I don't think that I'd notice the
> performance difference (it takes a fairly large difference to be
> noticeable without some yardstick).

I can guarantee you that the things I run on it there will be a 
noticeable difference, not just in performance but accuracy of 
computation. Right now I'm working on solution techniques for large 
games.. most of the computation is double-precision arithmetic. The more 
accurate the computations are, the less iterations the algorithm needs 
to do to ensure a certain tolerance/precision. So... any extra speed I 
get from using it as a desktop is just bonus.

At the moment I need to run my large jobs on remote servers; it'll be 
nice to run some of my large jobs overnight without worry that I'd be 
affecting other people's work and that they won't be affecting mine.

Marc

-- 
In the beginning the Universe was created. This has made a lot of
people very angry and has been widely regarded as a bad move.
   -- Douglas Adams
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists