# kernel 2.6.24 series

## maestax

Hi,

i have an ASUS laptop and till now i had gentoo 2.6.22-r9 running. Everything was fine, the responsiveness of the system was great and there was excellent performance.

i had tried the various 2.6.23 series but was disappointed by the performance i got.

Now, since 2.6.24 series has already been out, i decided to change my old kernel. I have installed the new 2.6.24-r4.

The first impression is again negative. I don' t know why i am losing on performance. I used the pretty much the same kernel configuration as in the 2.6.22-r9 which works great. Even when compiling the screen does not refresh smoothly. Of course, i have enabled 3d acceleration.

Even when changing between desktops, it takes about 2 seconds for the windows to appear their contents. Of course when i am using my laptop for work i can't accept it.

When i am writing in OpenOffice, the scrolling between pages is awful. I can't work...

Glxgears return the same results as with the 2.6.22-r9.

One thing i noticed is about the CPU. The steps of the cpufreqd are changed now. In 2.6.22-r9 i had 3 steps (930, 1300, 1833) while now i have many more steps starting from 250 and finishing in 1833. I have changed the cpufreqd.conf so as the minimum frequency would be 1145 MHz. I still have the above mentioned problems.

Could anyone help me with this? If i can't get this to work i am going back to 2.6.22-r9...

I think that there is something that i am missing...

Thank you...

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## punkmikey

Have you tried disabling CPU group scheduling in the kernel config? It was part of the CFS 'improvements' added.

I can't remember the exact name of the option, and I'm not currently near a Linux machine. I'll take a look when I got home as I seem to remember getting *much* better performance without it.

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## maestax

Thank you punkmikey.

I'm not sure, though, what exactly you mean... You mean the I/O schedulers or something else? I have set the I/O scheduler to CFQ.

Another thing is that even though i can play multiple videos with mplayer, when i load videos from youtube, the playback is very bad.

If you have any idea, please let me know...

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## notHerbert

Oh yah

I tried this, I disabled this

```
 General setup  ---> 

    [ ] Fair group CPU scheduler
```

Everything is working faster and somethings MUCH faster including emerge.

Awesome  :Very Happy: 

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## DaggyStyle

 *notHerbert wrote:*   

> Oh yah
> 
> I tried this, I disabled this
> 
> ```
> ...

 

ok, so why it is enabled by default?, there must be something else that it features or else it woundn't been enabled in the first place...

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## RoundsToZero

This is just speculation but it's meant to balance the load between users.  However on a desktop system there are generally only two, you and root.  In that case you probably just want whoever wants the CPU the most to get all of it instead of trying to balance it, since it's unlikely both would need the CPU at the same time.  On a server system with many (hundreds or more) users, balancing by user is more desirable.

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## notHerbert

 *RoundsToZero wrote:*   

> This is just speculation but it's meant to balance the load between users.  However on a desktop system there are generally only two, you and root.  In that case you probably just want whoever wants the CPU the most to get all of it instead of trying to balance it, since it's unlikely both would need the CPU at the same time.  On a server system with many (hundreds or more) users, balancing by user is more desirable.

 

Thanks RoundsToZero that's what I was thinking too.  I just thought to give punkmikey's suggestion a try and I like it - you know alone on my desktop. It's pretty pretty good  :Wink: 

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## DaggyStyle

can you link to a more official documentation?

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## notHerbert

 *DaggyStyle wrote:*   

> can you link to a more official documentation?

 

Well in my case I'm just having fun trying all sorts of things.  However here is surely a reliable source of good knowledge.   :Very Happy: 

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## punkmikey

As notHerbert says. The config option is under:

```
 General setup  --->

    [ ] Fair group CPU scheduler
```

Some people also notice a difference when switching between SLUB and SLAB allocators, also under General setup. Can't say I've noticed a difference personally though.

I hear people complaining about the kernel being more geared towards server usage than desktop usage, and the Fair group CPU scheduler is one thing that I would say defiantly benefits servers more than desktops. In my opinion, this sort of thing should be OFF by default. Server admins should know enough to be able to turn this on if needed. Although I would guess that most of them use a  pre-built kernel (such as redhat/CentOS), in which case the distro maintainers should decide whether or not to turn such features on.

Personally, I just read the changelogs at kernelnewbies to decide whether something should be turned on, and if in any doubt, just try it. Linux gives you the freedom and flexibility to do such a thing. Gentoo also give you the choice to try things with different packages via USE flags.

HTH!

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## maestax

Thanks guys for the answers.

I have tried disabling the mentioned option and the performance slightly improved.

But...

I returned to check once again the 2.6.22-r9 kernel and the difference is still HUGE!!!

2.6.22-r9 performs really great.

In 2.6.24-r4 even by disabling the CFS, i can't even scroll a word document smoothly... I can't play many videos without freezings... The responsiveness is very low and it is a problem for productivity...

I don't know what else to look for...

If you have any other ideas...

Thank you all anyway!  :Smile: 

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## notHerbert

Yep right on. 

I also notice zippier page loading in Firefox since enabling  

```
Networking --->

    Networking options  --->

        [*]   TCP: advanced congestion control  --->

            Default TCP congestion control (Vegas)
```

There are a bunch of them and this is my first attempt, so there may be better stuff .....   :Very Happy: 

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## Joseph_sys

 *notHerbert wrote:*   

> Oh yah
> 
> I tried this, I disabled this
> 
> ```
> ...

 

Where is that feature?

I' have genkernel 2.6.23-gentoo-r8 but this option is not there.

I'm experiencing the same problem when I compile sometimes the system is not responding for a 60-120sec when I enter the compiling screen.

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## jfp

maestax

Perhaps another thing to look at is:

```

Processor type and features

--> Timer Frequency

```

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## notHerbert

 *maestax wrote:*   

> In 2.6.24-r4 even by disabling the CFS, i can't even scroll a word document smoothly... I can't play many videos without freezings... The responsiveness is very low and it is a problem for productivity...

 

This is bigger than just a little tweaking will fix.  Since you are upgrading 2 releases you can't safely use your old .config.  I reckon you're going to have to diddle your new kernel configuration until you get it like you want it.

I'm trying to think of a specific suggestion, but really I think you need to go through it from top to bottom.  It's what I do for each new kernel release.   :Wink: 

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## maestax

Thank you all guys!!!  :Smile: 

After experimenting with the kernel i found the following:

1. The fair group CPU scheduler didn't affect the performance. I enabled it.

2. The High Resolution Timer Support increased the performance. I enabled it.

3. The parameter that was problematic was the "Single-depth WCHAN output". I disabled it.

I didn't make any more changes to the config of the 2.6.22-r9 kernel and everything seems to be working!

Thanks for the help!!!  :Smile: 

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## pappy_mcfae

How cool is this? I was just perusing the forum, and i happened upon this post. 

I was starting to get spooked here. My old Toshiba laptop had seemed kind of laggy the past few days. I've been setting up cross compilation, and I've had to do some work because of the 114 upgrades that hit about a week ago. I noticed that the compilation screens seemed to have even more lag in them than the old PII that recently was removed from service.

I just switched back over to 2.6.22-gentoo-r10, and what the heck do you know. There's the old snap back into the compile screens. Well, I guess that means we can chalk up yet another glitch to the 2.6.24.x kernel family. Now I have to set up 2.6.22.x kernels for this machine. I'm ok with that, really. It might make the machine run even faster, if such a thing is even possible. Who wants to fill out the bug report?

Blessed be!

Pappy

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## jfp

maestax,

 *Quote:*   

> 
> 
> 3. The parameter that was problematic was the "Single-depth WCHAN output". I disabled it.
> 
> 

 

I can't seem to find this parameter. Would you please indicate where it is?

Thanks!

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## jburns

"Single-depth WCHAN output" is only available with a 32 bit kernel.

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## Koda

it is under Processor type and features

my personal hint is moving from 250 to 300 Hz system, you could really feel the responsiveness

i fell for that fair cpu balancing, gonna fix next time i compile

about the High Resolution Timer, can we say that modern machines have this hardware support? how can we check?

is there somewhere besides the forum where we can share and read hints about kernel hacking?  :Smile: 

bye

Koda

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## maestax

 :Sad:   :Sad:   :Sad: 

Well, after some more tests the performance of 2.6.24 cannot be compared with that of 2.6.22-r9...

I have shorted out many problems and now i have no problems with the videos and other things.

BUT...

Even now, when compiling, the output is not smooth. When i press the "K menu" button in the KDE's taskbar, the menu takes a while to load. This is very weird. When i press the "Log out" option, the dark overlay that follows is moving in slow and not smooth way. All these are working fine under 2.6.22.

Another thing is that when idle the CPU runs at 1145 MHz and i experience the above problems. If i am compiling something and the CPU goes up to 1833 MHz, some of the problems go away (ex. the dark overlay when pressing "Log out").

Is there any other menu in the kernel's config apart from the ones mentioned to look for changes? Only CPU options matters or there exist other parameters that may influence?

Still searching...

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## pappy_mcfae

Just to make your problem more interesting, I noticed that 2.6.23-gentoo-r9 does the same thing during compilation. Konsole screens plod by instead of snapping. So, whatever the problem is, I think that it was born in the .23 kernel family.

Boy howdy, I sure hope they don't stop development on the .22 family.

Blessed be!

Pappy

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## maestax

Yes pappy_mcfae, you are right!

That is the reason i never used 2.6.23... But now we are 2 versions behind and i wanted to complete the transition.

But i cannot change the kernel and lose my performance...

I hope too that they don't stop the development on the .22...

 :Confused: 

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## Kosmas

maestax hi,

   just a stupid question If I may. Is there a possibility that the graphics driver is an ati or similar and it needs to compile again with the new kernel? Or for what it takes anything else like that which needs to be compiled across the new kernel?

Kosmas.

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## maestax

Hi Kosma!

The graphic driver is an ATI X1700.

Before testing the performance of each kernel i recompiled in order to enable 3d acceleration for my graphic card (set Direct Rendering = Yes). Both kernels are tested with 3d acceleration. That's why i don't think that graphic card is the problem.

Then, if something else needs to be compiled in the kernel, i really don't know... That's what i am looking for. If you have any ideas please let me know.

The options i play around are:

* Fair Group CPU Scheduler

* Control Group support

* SLAB allocator

* IO Schedulers

* Tickless System

* High Resolution Timer Support

* Single-depth WCHAN output

* Timer Frequency

* CPU idle PM support

What else should i check when configuring the kernel? What are the values you are using with a 2.6.24 kernel?

Thanks!  :Smile: 

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## Koda

maestax, about these options

* Fair Group CPU Scheduler

* Control Group support

* SLAB allocator

* IO Schedulers

* Tickless System

* High Resolution Timer Support

* Single-depth WCHAN output

* Timer Frequency

* CPU idle PM support 

did you enable or disable them?

you're heavily suggesting to downgrade to .22  :Razz: 

bye

Koda

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## maestax

Hi Koda,

I am trying to find the best combination of these options since they somehow affect the performance. I think that there must also be some other important options but i don't know yet...

Timer-Frequency has the greatest impact on the performance (acceptable values are 250Hz and 300Hz).

But playing around with the other options is not easy since the performance is getting a bit better or worse. But i haven't managed to bring the system to the performance of 2.6.22...

Anyone that uses 2.6.24 can help with these parameters??? Or any other options that would affect the problems of compiling not being smooth, slow responsiveness etc.

Thanks!  :Smile: 

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