# ck-sources : where is the staircase scheduler ? [SOLVED]

## brazzmonkey

there is something i am very good at : asking dumb questions. so here's another one.

i intend to give ck-sources a shot (i've always used gentoo-sources so far).

so i emerged the latest ck-sources, changed the linux symlink in /user/src, and started a make xconfig. here i realized my former kernel configuration was loaded (the one i copied on /boot). so i unmounted /boot and tried again. that looked ok except i couldn't find any entry about staircase scheduler.

i then remembered i read somewhere about the make mrproper thing, so i tried it, but eventually got the same stuff and staircase scheduler was still nowhere to be found.

i suppose i'm missing something, and hopefully you'll be able to enlighten me...

thanksLast edited by brazzmonkey on Thu Apr 27, 2006 3:18 pm; edited 1 time in total

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## sternklang

Hi,

If I'm not mistaken, staircase is the process scheduler built-in to ck kernels -- you don't need to do anything to enable it. You can change the parameters it uses with schedtool (emerge the package with that name). There are various unsupported kernels (look in the Unsupported Software forum for details) that let you choose different process schedulers if that's what you would like to do. 

The schedulers listed in the kernel config that you can change are the IO schedulers, and you can choose between those based on the role of your system (desktop, database server, etc.) and what kind of (mostly disk) IO load you have.

And it's not a dumb question -- the only dumb question is the unasked one!   :Smile: 

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## brazzmonkey

ok, so staircase scheduler is used by default.

you guessed right, i thought it should be listed in the i/o sheduler config sections, but from what you explain this is different stuff... (i know i still have many many things to learn in computing, especially in linux...)

i shall try schedtool too, then.

one last thing : i suppose trying to use my gentoo-sources' config with ck-sources is non-sense, isn't it ?

thanks a lot for your accurate answer sternklang !

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## sternklang

Glad to help!

ck-sources in Portage includes the Gentoo patchset, so using your gentoo-sources config won't break anything as the ck-specific config items will be added in when you "make menuconfig/xconfig/gconfig" (whatever choice for kernel building you use).

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## brazzmonkey

but i suppose this won't work with beyond-sources, which i'm compiling right now... nevermind, this is a good way to learn what's in linux kernel !

thanks again for all those precious infos sternklang !

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## bollucks

If you use your old config and update it by running "make oldconfig" or "make menuconfig" or equivalent ON the config file it will be updated accordingly. It almost makes no difference which kernel you start with; this should work safely.

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## brazzmonkey

the gentoo docs say that using make oldconfig is ok for minor updates of the same kernel family only

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## bollucks

 *brazzmonkey wrote:*   

> the gentoo docs say that using make oldconfig is ok for minor updates of the same kernel family only

 

Having built kernels from 2.0.36 days till now I can tell you it works well for any 2.6 kernels. A jump from 2.4 to 2.6 wouldn't tolerate it, but any 2.6 kernel would.

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## syg00

 *bollucks wrote:*   

> A jump from 2.4 to 2.6 wouldn't tolerate it, but any 2.6 kernel would.

 Wanna bet   ... ???    :Twisted Evil: 

I decided to try slack a while back (work laptop), and Pat ships 2.4 by default. Had a hell of a job getting his 2.6 kernel (from extras) working, so pulled a clean kernel.org download.

"make oldconfig" worked fine - despite what everyone on the Slack lists said. Took a while to get through the new options, but the system built first time. This was probably around the 2.6.10 timeframe.

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## brazzmonkey

well that's good news then. i don't have so much experience in kernel compiling so i trust you.

i thought i was weird having such a tool and not being to use it for (major) kernel upgrades. maybe i'll try it next time.

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## brazzmonkey

can anyone explain how to use schedtool ?? i went through the man pages but in the end i am even more confused...

also i've found this which i think i'm gonna try.

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## bollucks

 *brazzmonkey wrote:*   

> can anyone explain how to use schedtool ?? i went through the man pages but in the end i am even more confused...
> 
> also i've found this which i think i'm gonna try.

 

If you want to run an ultra low priority (idle only) task say mprime

schedtool -D -e mprime

If you want to run a pseudo real time task say mplayer

schedtool -I -e mplayer

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## brazzmonkey

good !

thanks for this, bollucks ! this is human understandable stuff (or should i say brazzmonkey understandable stuff ??) !

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## bollucks

 :Very Happy: 

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## sundialsvc4

What I do is ...   (Always) save the existing .config file somewhere far away .. namely, in a subdirectory of "/root" which is devoted to this purpose.  make oldconfig (maybe this or "defconfig") just to get started.  Use diff to see exactly what the changes were.  make menuconfig to see and review and make final changes to what was done.  Always make clean (or similar) to ensure that everything will be recompiled.  (Maybe: rename the config, make distclean, rename it back.  That works.) 

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