CPU performance problem on old laptop
fry.kun at gmail.com
Mon Dec 17 05:00:25 UTC 2007
Konstantin Svist wrote:
> Hi all,
> I'm investigating slowness on my old laptop (HP ze4400, circa 2004;
> see related thread "hdparm shows poor performance on cached reads for
> PATA drive" if you're interested).
> Apparently the HD cached read speed is not the only thing that
> suffered a performance hit.
> I ran nbench (http://www.tux.org/~mayer/linux/bmark.html) on the
> laptop and got the results that showed that the performance is roughly
> half of my newer laptop (Dell E1505) - which was very surprising,
> since the new laptop is not THAT much more powerful than the old one
> (plus, I'm pretty sure the test didn't use both cpu cores on the new
> I decided to try nbench in knoppix environment - and to my surprise,
> it performed nearly as well as (and in a few tests, better than) the
> new laptop!!
> I've ran the same test on the new laptop in knoppix - and found that
> the results weren't affected all that much.
> I've also tried nbench on the old laptop in runlevels 3 and 1: 3 gives
> same performance as 5, but 1 gets somewhere in the middle between
> knoppix and F8/runlevel 5.
> What should I investigate next, to find the cause?
> What do the results so far suggest? I'm guessing some part of the
> problem is the services that start up in init 3/5 - and perhaps the
> new kernel can be partially blamed, as well
> Has anyone else experienced a problem like this? What can be done
> about it?
Answering my own question
After some more digging: apparently the resource hog was wdaemon (daemon
that emulates a drawing tablet so that it can be hotplugged into X).
This was a surprise since my new laptop also has the same one installed
- and doesn't exhibit the slowdown.
I've emailed the maintainer and asked him to check out the problem.
Another service that affected the speed was cpuspeed - but that's only
when "performance" was not selected as the current profile.
P.S. Apparently this was the same issue as the HD performance indicated
by hdparm - who knew :)
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