Running with the brakes on ...

[Paul Reilly]

William Cohen wrote:
> Adam Jackson wrote:
>> On Mon, 2006-12-04 at 02:13 -0500, Paul Michael Reilly wrote:
>>
>>
>>> When running top, I see that X is consuming 40% of memory which is not
>>> surprising since I am running two X sessions with 3200x1200 (dual
>>> head, radeon, open source) along with long running firefox,
>>> thunderbird and VNC (also 3200x1200) apps).  But when I bring up the
>>> Soundcard Detection tool under KDE top shows Xorg is consistently
>>> grabbing 93% of the CPU even when all I am doing is typing this
>>> message.  That would certainly explain a lot of the lag in response to
>>> mouse clicks from the app. :-)  Switching to Gnome and running top
>>> there shows varying, but high (60%ish) CPU use with the Soundcard
>>> Detection tool still running in both sessions.  But with Gnome,
>>> response to mousee clicks is fine, even with the high X CPU use.
>>
>>
>> So you've found that some use profile makes X use all the CPU.  Now you
>> need to find out _what_ in X is taking all the time.  You need to either
>> use a tool like oprofile or sysprof to extract that information, or you
>> need to instrument the X server to report on what requests and clients
>> are using most of its time.  The latter requires code changes to a
>> project that many people find intimidating and/or unpleasant to work
>> with, which is why I suggested using oprofile in the first place.
>>
>> - ajax
>>
>
> Yes, certainly use OProfile to narrow down what code/package is using 
> the CPU. If you are not familar with OProfile, there are some writeup 
> on how to use OProfile to track down this kind of problem at:
>
> http://people.redhat.com/wcohen/
>
> In particular the following articles would be a good place to start:
>
> http://people.redhat.com/wcohen/FedoraCore2OProfileTutorial.txt
> http://www.redhat.com/magazine/012oct05/features/oprofile/
>
> You will probably need to install some debuginfo RPMs when doing the 
> analysis of the collected data to see exactly which functions are 
> using up the time. These can be install via yum.
>
> -Will
Thanks Will.  This is exactly what I was hoping to hear.  Forgive me a 
small moment but this is just so much more productive and effective in 
motivating me to help Fedora than the terse,

"use oprofile"

message that I received twice.

-pmr